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Best Practice of HUAWEI OceanStor T Series Solutions for Key VMware Applications

Issue 1.0 (2012-07-06) Huawei Proprietary and Confidential

Copyright © Huawei Technologies Co., Ltd.

i

Copyright © Huawei Technologies Co., Ltd. 2013. All rights reserved.

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Best Practice of HUAWEI OceanStor T Series Solutions

for Key VMware Applications About This Document



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About This Document

Purpose

This document describes the best practice for using HUAWEI OceanStor T series on the

VMware vShpere 5.0 platform, including network design, configuration method and

performance tuning for storage systems and VMware virtual machines (VMs). The best

practice in this document can meet the requirements of configuration optimization in a variety

of application scenarios.

Intended Audience

This document is intended for:

Marketing engineers

Technical support engineers

Maintenance engineers

Symbol Conventions

The symbols that may be found in this document are defined as follows.

Symbol Description

Indicates an imminently hazardous situation which, if not

avoided, will result in death or serious injury.

Indicates a potentially hazardous situation which, if not

avoided, could result in death or serious injury.


avoided, may result in minor or moderate injury.


avoided, could result in equipment damage, data loss,

performance deterioration, or unanticipated results.

NOTICE is used to address practices not related to personal

injury.


for Key VMware Applications About This Document



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Symbol Description

Calls attention to important information, best practices and

tips.

NOTE is used to address information not related to personal

injury, equipment damage, and environment deterioration.


for Key VMware Applications Contents



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Contents

About This Document .................................................................................................................... ii

1 Overview ......................................................................................................................................... 1

2 Component Introduction ............................................................................................................. 2

2.1 Introduction to HUAWEI OceanStor T Series Storage Systems................................................................................... 2

2.2 Introduction to VMware vSphere ................................................................................................................................. 4

3 Storage Network Design .............................................................................................................. 6

3.1 Reliability Design ......................................................................................................................................................... 6

3.2 Bandwidth Design ........................................................................................................................................................ 7

3.3 Load Balancing Design ................................................................................................................................................. 7

3.4 Network Design ............................................................................................................................................................ 7

4 Optimizing Storage System Configuration ............................................................................. 8

4.1 Configuration Process ................................................................................................................................................... 8

4.2 Selecting Disks ............................................................................................................................................................. 8

4.3 Configuring RAID Groups ........................................................................................................................................... 9

4.3.1 RAID Group Levels ................................................................................................................................................... 9

4.3.2 RAID Group Capacity ............................................................................................................................................. 10

4.3.3 Hot Spare Disk and Reliability ................................................................................................................................ 10

4.3.4 RAID Group Performance Evaluation ..................................................................................................................... 10

4.4 LUN Configuration ..................................................................................................................................................... 12

4.4.1 Owning Controller ................................................................................................................................................... 12

4.4.2 Stripe Depth ............................................................................................................................................................. 12

4.4.3 Prefetch Policies ...................................................................................................................................................... 12

4.4.4 Write-Back Policies ................................................................................................................................................. 13

4.5 Host Mappings ............................................................................................................................................................ 13

5 VM Configuration Optimization ............................................................................................. 14

5.1 VMFS and RDM ......................................................................................................................................................... 14

5.2 Suggestion on VMFS Volume Configuration ............................................................................................................. 17

5.2.1 Suggestion on Capacity Configuration .................................................................................................................... 17

5.2.2 VMFS Volume Expansion ....................................................................................................................................... 17

5.2.3 Exclusive Volume or Shared Volume ....................................................................................................................... 18

5.3 Suggestion on Virtual Disk Configuration .................................................................................................................. 19


for Key VMware Applications Contents



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5.3.1 Choosing a Virtual Disk Format .............................................................................................................................. 19

5.3.2 Virtual Disk Modes .................................................................................................................................................. 20

5.3.3 SCSI Bus Sharing Methods ..................................................................................................................................... 20

5.3.4 Configuring Partition Alignment ............................................................................................................................. 21

5.4 Suggestion on RDM Configuration ............................................................................................................................ 22

5.5 Configuring I/O Queue Depth .................................................................................................................................... 22

5.6 DRS and HA Are Recommended ................................................................................................................................ 23

6 Summary ....................................................................................................................................... 25

A Glossary ....................................................................................................................................... 26


for Key VMware Applications 1 Overview



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1 Overview

With the advent of virtualization, companies are falling over themselves to deploy VMware

VM-based applications. HUAWEI OceanStor T series storage systems have been optimized

for VMware VMs and offer comprehensive solutions in the infrastructure, service key

applications, and backup and disaster recovery of virtual data centers. This document

introduces how to select the proper storage system on the VMware vSphere 5.0 platform,

including storage system selection, storage system network design, storage system

configuration optimization, and the configuration optimization of the VMware vSphere

platform. You can achieve the best performance and reliability by configuring the storage

system as recommended in this document.

If you are deploying storage systems on the VMware platform, you are advised to configure

the storage systems as recommended in this document.


for Key VMware Applications 2 Component Introduction



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2 Component Introduction

About This Chapter

2.1 Introduction to HUAWEI OceanStor T Series Storage Systems

2.2 Introduction to VMware vSphere

2.1 Introduction to HUAWEI OceanStor T Series Storage Systems

Targeted at high-level storage applications, HUAWEI OceanStor T series is developed on

industry-leading hardware, high-density disk design, TurboModule high-density I/O modules,

and the hot swap design. Besides, HUAWEI OceanStor T series integrated a variety of

advanced technologies, including the TurboBoost three-level performance acceleration

technology and multi-data redundancy technology. These technologies not only meet the

requirements of big database OLTP/OLAP, high-performance computing, digital media,

Internet operation, integrated storage, backup, disaster recovery, and data transfer, but also

ensure service security and continuity.

Figure 2-1 HUAWEI OceanStor T series storage systems





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More importantly, Huawei S5500T/S5600T/S5800T/S6800T comes with such features as high

performance, high reliability, high scalability, and low power consumption.

Table 2-1 Features provided by HUAWEI OceanStor T series storage systems

High Performance

SmartCache

The SmartCache resource pool consists of one or

multiple SSDs. By collecting the real-time

information about the access frequency of the data

blocks in the storage system, SmartCache

dynamically transfers the hotspot data blocks with

high access frequency from the HDD to the

SmartCache resource pool. Because an SSD has a

faster access speed, SmartCache improves the

read-performance and the access efficiency of the

host.

Cache intelligent

prefetch

Cache intelligent prefetch can identify the current I/O

sequence and enable/disable the Cache prefetch

function based on different service models. Based on

different application scenarios, you can set the

optimized prefetch length by using Cache intelligent

prefetch. In addition to significantly improving the

host read performance, Cache intelligent prefetch

reduces disk access frequency, prolonging disk

lifespan.

Dual-controller

dynamic load

balancing

Working in an Active-Active mode, the two

controllers can concurrently process the I/O requests

from the host and share the data storage loads. This

avoids the situation that one controller is over loaded

but the other one is left unused. The dual-controller

dynamic load balancing not only reduces the load on

a single controller, but also utilizes system resources

more properly, improving both system efficiency and

performance.

VAAI VM

performance

acceleration

The VMware VAAI technology is supported. VAAI

can significantly improve the usage effectiveness of

the storage space in S5600T on the VMware platform

and balances loads between the server on the

VMware platform and the storage system, reducing

load on the host and improving storage efficiency.





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High Reliability

Built-in

BBUs+data

coffers

The built-in BBUs+data coffers design is used.

Small, low-cost, redundant, and hot swappable,

built-in BBUs can supply power to controllers and

the coffer after the external power fails. Data in

caches can be written into disks after the external

power failure, and data integrity and reliability are

protected.

Disk pre-copy After obtaining the firsthand disk status information

by using the disk predicting technology, disk

pre-copy uses the pre-copy algorithms to analyze

disk running status to calculate the probability of disk

failure. If some disks are predicted to fail, disk

pre-copy copies the data in those disks to a hot spare

disk. This predicting act not only shortens the time

needed for reconstruction or eliminates the necessity

for reconstruction after disk failure but also reduces

the possibility of disk failing again during

reconstruction, improving storage security.

Critical data

protection

HyperImage (virtual snapshot), HyperCopy (LUN

copy), HyperMirror/S (synchronous copy), and

HyperMirror/A (asynchronous copy) are used to

meet the requirements of backup, disaster recovery,

and data transfer.

2.2 Introduction to VMware vSphere

By using the virtualization products offered by VMware, you can run multiple operating

systems in one physical machine. For each operating system, you can set virtual partitions and

configuration and switch one operating system to another.

VMware vSphere is a suite released by VMware for data centers. VMware vSphere transfers

data centers to a simplified cloud computing infrastructure by using virtualization, enabling IT

departments to provide flexible and reliable IT services. In addition to vitalizing and

integrating basic physical hardware resources, VMware vSphere provides abundant virtual

resources for data centers.

VMware vSphere consists of the following component layers:

Table 2-2 VMware vSphere components

Name Description

Infrastructure service Infrastructure service The basic architecture service is a service set

used for collecting, integrating, and allocating hardware basic

architecture resources. It includes vComputer, vStorage, and

vNetwork, which are responsible for vitalizing computing

resources, storage resources, and network resources respectively

and integrating the resources in a virtual environment for unified

management.





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Name Description

VMware

vCenter

Server

VMware vCenter Server provides a unified management platform

for data centers and basic data center services, such as access

control, performance monitoring, and configuration.

Client You can access the VMware vSphere data center management

platform using vSphere Client or Web Access (on a Web browser).

In addition to solving the problems of over-complexity, low efficiency, and inflexibility

occurring in data center deployment, VMware reduces the cost of physical basic architecture,

reduces the operating expenses of data centers, and improves work efficiency, flexibility, and

response speed.

Besides, VMware vSphere provides a host of high-availability technologies, such as HA, DRS,

and FT. The latest 5.0 VMware vSphere provides powerful capacities in basic architecture

virtualization and extension.


for Key VMware Applications 3 Storage Network Design



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3 Storage Network Design

About This Chapter

3.1 Reliability Design

3.2 Bandwidth Design

3.3 Load Balancing Design

3.4 Network Design

3.1 Reliability Design

A SAN network design must support link redundancy, switch redundancy, controller

redundancy and prevents single points of failure (SPOFs). Figure 3-1shows a typical network

diagram used by OceanStor T series in a virtual environment. In the network, there are at least

two data channels between each host and LUN, and the data access must pass different

switches and controllers.

Figure 3-1 Typical network diagram used by OceanStor series in a virtual environment


for Key VMware Applications 3 Storage Network Design



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3.2 Bandwidth Design

When designing an SAN network, you must choose the proper OceanStor T series storage

systems based on the bandwidth requirements of application systems (for details about

bandwidth performance, see the white papers and brochures of Huawei storage systems) and

configure enough physical channels for ESX cluster to prevent the front-end links from

becoming a performance bottleneck.

3.3 Load Balancing Design

In a SAN network design, load balancing on controllers and links must be supported. Figure

3-1 shows the typical network which allocates LUNs equally on controllers. The proper

multipathing configuration of OceanStor T series must be selected on ESX Server, and the

fixed mode is recommended for VM path selection strategy to ensure link redundancy and

load balancing on transmission paths.

3.4 Network Design FC network

FC network is a relatively mature storage network configured on the VM platform. To

establish connection between ESX servers and storage systems, HBAs must be

configured on the ESX host. Each HBA has a WWN as their unique identifier. The

following configurations are recommended for FC network configuration:

− When using an FC network, you must use the HBAs with at least two ports to ensure

link redundancy.

− You are advised to use only the FC Zone function and to assign links of the same type

to the same FC Zone to prevent cross-network effects.

SCSI network

Both HUAWEI OceanStor and VMware vSphere support 10GE network configuration.

Because performance of a single port is improved, the number of network ports can be

considerably reduced, especially for blade severs.

The following configurations are recommended for ISCSI configuration:

− On the ESX server, the flow control function can be configured for each network port.

You are advised to disable the flow control function to maximize the performance of

the storage system.

− HUAWEI OceanStor T series and VMware vSphere 5.0 support Jumbo frame. You

are advised to enable the Jumbo frame function to significantly improve network

performance. (The network switch also needs to support the Jumbo frame function.)

− Because the IP network may conflict with the management network, you are advised

to separate the iSCSI network from the port management network by configuring

them to different network segments or VLANs.


for Key VMware Applications 4 Optimizing Storage System Configuration



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4 Optimizing Storage System Configuration

About This Chapter

4.1 Configuration Process

4.2 Selecting Disks

4.3 Configuring RAID groups

4.4 Configuring LUN

4.5 Configuring Host Mappings

4.1 Configuration Process

Figure 4-1 shows the configuration process of HUAWEI OceanStor T series, and this section

describes configuration optimization from the following perspectives:

Figure 4-1 Storage system configuration process

Select disksConfigure RAID

groupsConfigure LUNs

Configure and use

LUNs on the VMware

platform

Configure host

mappings

4.2 Selecting Disks

Because OceanStor T series supports a variety of disks with different capacities and supports

the mixture use of different disks, you can choose proper disks to configure the VM storage

based on the requirements of your services. Table 4-1 lists the random access IOPS empirical





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values of some disk capacities and small data blocks, and the values can serve as references

for you.

Table 4-1 Disk capacity and performance

Disk Type Capacity Random IOPS Application Scenario

SATA 7.2k rpm 1 TB / 2 TB 30 - 60 Backup and archiving

SAS 15k rpm 300 GB / 450 GB /

600 GB

100 - 200 Video, file service, and database

SATA SSD 50 GB / 100 GB /

200 GB

1500 - 2500 Database and email service

4.3 Configuring RAID Groups

4.3.1 RAID Group Levels

You need configure the RAID groups based on the data features of different transactions, and

Table 4-2 lists the suggestion.

Table 4-2 RAID group configuration for different transactions

Transaction Category

Data Characteristic Configured RAID Level

Configured Disk Type

Sequential I/Os in

transaction log disks

Sequential I/Os,

requiring high reliability

RAID 10 SAS/FC

OLTP database data

Exchange Server data

database RAID 10 SAS/FC

Backup and archiving Large capacity RAID 5/RAID 6 SATA

Java applications and

Web applications

Non-dense I/Os RAID 5 SAS/FC

File services and

video applications

Random big I/Os RAID 5 SAS/FC

VM boot disk Low I/O load, requiring

swift response

RAID 5 SAS/FC

CAUTION

Do not use RAID 3 except for large-block sequential reads, such as non-linear editing.

Do not use RAID 0 unless otherwise specified.





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4.3.2 RAID Group Capacity

Recommended configuration:

The number of disks in a RAID group should range from 5 to 12. If the number is

smaller than 5, the performance of the RAID group is relatively poor, followed by the

requirement for more RAID groups and the increase in maintenance cost. For a RAID 5,

RAID 6, or RAID 3 group, this may result in a waste of storage space. On the contrary, if

the number is greater than 12, the RAID group is reconstructed when disk failure occurs.

When more disks are required, the probability of multi-disk failure becomes higher and

the system reliability will decrease accordingly.

An odd number of disks are recommended for a RAID 5 group, and five or nine disks are

preferred.

An even number of disks is recommended for a RAID 6 group, and six or ten disks are

preferred.

Dual-disk mirroring is recommended for a RAID 10 group except for the applications

that demand ultra-high reliability.

Eight or twelve disks are recommended for a RAID 10 group with dual-disk mirroring.

4.3.3 Hot Spare Disk and Reliability

Any disk may fail in use. Therefore, for data security, you must create hot spare disks for an

OceanStor storage system and determine the number of hot spare disks based on the reliability

requirement, maintenance cost, and number of RAID groups. You are advised to configure at

least one hot spare disk in each disk enclosure.

4.3.4 RAID Group Performance Evaluation

The random read and write performance of a RAID group can be evaluated by the random

performance of a single disk, and the bandwidth of a RAID group is determined by the

front-end host channels and back-end storage channels. The following formulas are used to

compute the random performance of different RAID groups. You can refer to these formulas

in actual application scenarios.

RIOPSRAID

indicates the random read IOPS performance of a RAID group.WIOPSRAID

indicates the random write IOPS performance of a RAID group.

IOPSDISK

indicates the random IOPS performance of a single disk (with no notable

difference between HDD random read and write performance).

RMBPSRAID

indicates the sequential read bandwidth performance of a RAID group.

RMBPSRAID

indicates the sequential write bandwidth performance of a RAID group.

MBPSPATH

indicates the bandwidth at the back-end channels of a RAID group.

MBPSDISK

indicates the sequential bandwidth performance of a single disk.

N stands for the number of member disks in a RAID group (5 ≤ N ≤ 12) with the

hypothesis that the front-end channels are not the performance bottleneck.

RAID 0

RAID 0: a striped volume of hard disks. The sequential bandwidth is equal to the

channel bandwidth performance or the total bandwidth performance of all disks. The

random read and write performance is equal to the total random performance of all disks.

RMBPSRAID0 = WMBPSRAID0 = MIN (MBPSPATH, MBPSDISK x N)

RIOPSRAID0 = W IOPSRAID0 = IOPSDISK x N





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RAID 10

RAID 10: a stripe of mirrored hard disks. RMBPSRAID10 = MIN (MBPSPATH,

MBPSDISK x N) WMBPSRAID10 = 1/2 x MIN (MBPSPATH, MBPSDISK x N)

RIOPSRAID10 = IOPSDISK x N

W IOPSRAID10 = 1/2 x IOPSDISK x N

RAID 5

RAID 5: block-level striping with parity data distributed across all member disks.

RMBPSRAID5 = MIN (MBPSPATH, MBPSDISK x N) WMBPSRAID5 = (N-1)/N x

MIN (MBPSPATH, MBPSDISK x N) RIOPSRAID5 = IOPSDISK x N

WIOPSRAID5 = 1/4 x IOPSDISK x N

RAID 6

RAID 6: block-level striping with two copies of parity data distributed across all member

disks.

RMBPSRAID6 = MIN (MBPSPATH, MBPSDISK x N)

WMBPSRAID6 = (N-2)/N x MIN (MBPSPATH, MBPSDISK x N)

RIOPSRAID6 = IOPSDISK x N

WIOPSRAID6 = 1/6 x IOPSDISK x N

CAUTION

The random IOPS formulas in the preceding formulas are not applicable to an SSD, because

there is notable difference between the random read performance and random write

performance of an SSD. IOPSDISK

in RIOPSRAID

and WIOPSRAID

formulas can be replaced

with RIOPSSSD

and WIOPSSSD

respectively for rough computation. Note that because SSDs

have high random performance, the maximum IOPS of the storage system must be considered

when you are computing the random performance of a RAID group.

The preceding formulas are used to compute the bandwidth and IOPS of a 9-disk RAID 5 and

an 8-disk RAID 10.

Suppose IOPSDISK

= 200, MBPSDISK

= 150 MB/s, and the back-end storage uses one 4 Gbit/s

SAS/FC loop, then MBPSPATH

= 4 x 1000 x 1/8 x 8/10 = 400 MB/s (1/8 is the conversion

from bit to byte and 8/10 is the bandwidth loss in the 8 bit/10 bit conversion).

For a 9-disk RAID 5group:

RMBPSRAID5 = MIN (400, 150 x 9) = 400 MB/s WMBPSRAID5 = 8/9 x MIN (400,

150 x 9) = 355 MB/s RIOPSRAID5 = 200 x 9 = 1800

WIOPSRAID5 = 1/4 x 200 x 9 = 450

For an 8-disk RAID10 group:

RMBPSRAID10 = MIN (400, 150 x 8) = 400 MB/s WMBPSRAID10 = 1/2 x MIN

(400, 150 x 8) = 200 MB/s RIOPSRAID10 = 200 x 8 = 1600

WIOPSRAID10 = 1/2 x 200 x 8 = 800





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4.4 LUN Configuration

4.4.1 Owning Controller

The OceanStor T series storage systems use two controllers that work in the active-active

mode, and each LUN has its owning controller. Under normal circumstances, the I/O

operations on a LUN are processed by its owning controller, and the other controller takes

over services only when the host access path or the owning controller fails.

You are advised to assign the LUNs with heavy loads to both controllers equally to ensure

load balancing and improve application performance.

4.4.2 Stripe Depth

OceanStor T series storage systems offer multiple striping policies that bring great flexibility

in application configuration. The LUN stripe depth must be determined based on the I/O size.

Table 4-3 lists the typical configurations.

Table 4-3 Typical stripe depths

RAID Level Stripe Depth

RAID 0 256k / 512k

RAID 5 64k / 128 k

RAID 10 256k / 512k

In addition, you must take the server system stripe into consideration when configuring stripes.

For example, if you use ASM disks (whose default stripe depth is 1 MB) in Oracle databases,

you must configure the stripe of the storage system to a value that can be exactly divided by 1

MB. The stripe depth of 256 KB is recommended for an 8-disk RAID 10, and 128 KB is

recommended for a 9-disk RAID5.

4.4.3 Prefetch Policies

OceanStor T series storage systems offer four prefetch policies which can be applied to most

applications. If applications have high randomicity, configure non-prefetch for them.

Constant prefetch: prefetches a constant size of data from hard disks when hit fails and

applies to large-block sequential read.

Multiplied prefetch: prefetches a certain amount (a multiple of missed I/O amount) of

data from hard disks when hit fails and applies to small-block sequential read.

Intelligent prefetch: automatically determines whether to prefetch data according to the

load characteristics when hit fails. OceanStor T series intelligently calculates the amount

of the data to be pre-fetched. Intelligent prefetch applies to most applications.

Non-prefetch: does not prefetch data and applies to random services.

Intelligent prefetch is recommended for common OLTP database applications.





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4.4.4 Write-Back Policies

OceanStor T series provides sound power failure protection and uses the write-back

technology, which greatly shortens I/O delay and improves application performance. The

write-back with mirroring mechanism applies to most applications. For those applications that

demand high reliability, use write-through not write-back without mirroring for LUNs.

Write-back with mirroring: After receiving a write I/O request from the host, the current

controller writes this I/O request into the cache of the other controller, then writes this

I/O request into its own cache, and then notifies the host that the write I/O operation is

completed. The current controller flushes the cache data onto hard disks by using a policy,

ensuring that the cache always has enough space for new write I/O requests. The

write-back with mirroring mechanism ensures data reliability when a controller fails.

Write-through: After receiving a write I/O request from the host, the current controller

first writes this I/O request into its memory, then writes this I/O request into its disk, and

then notifies the host that the write I/O operation is completed. The write-through

mechanism applies to the application scenarios that demand ultra-high data reliability.

Write-back without mirroring: After receiving a write I/O request from the host, the

current controller first writes this I/O request into its memory, and then notifies the host

that the write I/O operation is completed. Because the write-back without mirroring

mechanism may cause data loss, it is not recommended for LUNs.

Write-back with mirroring is recommended to ensure high performance and high reliability of

storage systems.

4.5 Host Mappings

You can map host configuration to a host or host group. You must consider the following

situations when configuring mappings:

1. If such high-availability functions as HA and DRS are enabled on the VMware platform,

all ESX hosts must be able to see the same storage system. Therefore, you need to add all

ESX hosts to the host group and map LUNs to the host group.

2. If some host cluster functions need to use quorum disks, such as the Oracle RAC quorum

disk and Microsoft cluster quorum disk, multiple ESX hosts can access the same disk.

Therefore, you need to add the ESX hosts to the host group and map LUNs to the host

group.


for Key VMware Applications 5 VM Configuration Optimization



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5 VM Configuration Optimization

About This Chapter

5.1 VMFS and RDM

5.2 Suggestion on VMFS Volume Configuration

5.3 Suggestion on Virtual Disk Configuration

5.4 Suggestion on RDM Configuration

5.5 Configuring I/O Queue Depth

5.6 DRS and HA Are Recommended

5.1 VMFS and RDM

As a clustered file system with high performance, VMware Virtual Machine File System

(VMFS) enables multiple VMs to access an integrated clustered storage pool, significantly

improving resource utilization rate. By using VMFS, you can create a small number of LUNs

with a big capacity and allocate the LUNs to different VMs. Figure 5-1 displays the schematic

drawing of VMFS.

Figure 5-1 VMFS schematic drawing





15

Two VMFSs are available in VMware VMs: VMFS-3 and VMFS-5. VMFS-5 optimized

VMFS-3 performance, such as supporting disks with a bigger capacity. You are advised to

adopt VMFS-5 to use its new features.

VMFS-3 VMFS-5

Supports up to a 2 TB disk volume. Supports up to a 60 TB disk volume, including

RAW Device Mapping (RDM) disks.

Supports master boot record (MBR)

partition.

GUID partition table (GPT) supports a bigger

capacity.

Data block sizes include 1 MB, 2

MB, 4 MB, and 8 MB.

Has a unified data block size of 1 MB and supports

256 GB or larger files.

The smallest sub-block size is 64

KB.

The sub-block size is 8 KB, occupying smaller

space.

The maximum number of files is

30720. Each volume supports over 100,000 files.

The largest VMDK file size is 2 TB. The largest VMDK file size is 2 TB.

Supports up to 256 LUNs. Supports up to 256 LUNs.

Uses the SCSI reservation

mechanism to lock the whole LUN.

Uses VAAI hardware-assisted locking to reduce

disk access conflicts.

VMFS supports RDM.RDM can use a VM to access the physical sub-storage system, but the

sub-storage system can only use FC or iSCSI. Figure 5-2 displays RDM schematic drawing.

VMFS provides a basic symbolic link which is used in VM configuration. When the VM

needs to open an RDM device, it first opens the symbolic link. After the symbolic link

file .vmdk resolves the address and finds the mapped physical device, follow-up read and

write operations do not have to go through VMFS volume, and the physical device is operated

by the VM.





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Figure 5-2 RDM schematic drawing

There is no notable difference between the performance of VMFS and RDM. For random I/O

loads, VMFS and RDM have similar performance in throughput. As for sequential I/O loads,

RDM has relatively better performance than VMFS. For details about the performance of

VMFS and RDM, see the Performance Characterization of VMFS and RDM Using a SAN.

Application scenarios of MFS and RDM:

The VMFS is preferred unless otherwise specified.

RDM applies to the following application scenarios:

Choose RDM for P2V or V2P.

Choose RDM when physical machines and VMs are used for cluster.

RDM disks with physical compatibility are recommended for VMs that use Microsoft Cluster

Services (MSCS).





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5.2 Suggestion on VMFS Volume Configuration

5.2.1 Suggestion on Capacity Configuration

VMFS-5 uses 1 MB data block and 8 KB sub-block and supports 256 GB or larger files, with

smaller files occupying less space. The VMFS volume supports a maximal capacity of 60 TB.

You are not advised to create a RAID group with an excessively large capacity, because if a

physical hard disk fails, the RAID group needs to be reconstructed, and the reconstruction

may affect services.

5.2.2 VMFS Volume Expansion

The expansion function allows the VMFS to cross multiple LUNs. The expansion function

allows the VMFS to cross multiple LUNs. In this application scenario, LUNs are arranged

linearly. Space in the first LUN is used first, and space in the following LUNs will be used

only when space in the first LUN is used up. As a result, the VMFS cannot balance I/O load

among the LUNs to improve the application performance, but can simplify storage

management and realize thin-provisioning at the application layer.

If the application has a light I/O load but demands large storage space, you can create a VMFS

volume across multiple LUNs; if the application has a heavy I/O load, you are advised to

create multiple virtual disks for the VM and assign them to multiple VMFS volumes.

Figure 5-3 VMFS volume expansion





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5.2.3 Exclusive Volume or Shared Volume

ESX administrators' top concerns may involve how many VMs a VMFS volume is assigned to

and how to assign VMFS volumes to VMs of different applications. A lot of factors must be

considered when determining whether to allow multiple VMs to share a big VMFS volume or

allow each VM to have its own relatively smaller VMFS volume.

Figure 5-4 VMFS exclusive volumes and shared volume

Table 5-1lists the advantages and disadvantages of the two volume types. Choose the proper

type for your configuration based on management cost, performance, and extensibility.

Table 5-1 Advantages and disadvantages of exclusive VMFS and shared VMFS

Exclusive VMFS Shared VMFS

Maps one VMFS volume to one

VM.

Multiple VMs share one VMFS volume.

Poor resource utilization. Improved resource utilization.

Deployed in isolation. Easy deployment.

Requires more management cost. Requires lower management cost.

Applicable to applications with

big I/Os.

Resource competition may exist, compromising I/O

performance.

If shared storage with exclusive volumes is used, a large number of disks with high I/O workloads are

configured exclusively to ensure the performance of applications with high throughput. Shared storage

can be used to configure other storage systems.





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5.3 Suggestion on Virtual Disk Configuration

5.3.1 Choosing a Virtual Disk Format

The VMFS supports the following virtual disk formats:

Thin: assigns space on demand.

Thick: assigns a fixed amount of space. The Thick format includes the following

sub-formats:

− Zeroed Thick: generates VMDK files with a fixed size and does not write data into

disks.

− Eager Zeroed Thick: generates VMDK files with a fixed size and writes 0 into disks.

Figure 5-5 shows that there is no notable difference between the performance of Thin and

Zeroed Thick. (For details, see Performance Study of VMware vStorage Thin Provisioning.)

Compared with the other two formats, Eager Zeroed Thick has better performance in

sequential write and has no notable performance difference in other I/O modes.

Virtual disks of each format can be expanded to a larger capacity, but no virtual disk can

decrease the actual used space.

Figure 5-5 Comparison of the performance of different VMFS disk formats

Remarks: The figure above is from Performance Study of VMware vStorage Thin Provisioning.

Zeroing: All VMFS blocks must be zeroed out before data is written into them.

Post-zeroing: All VMFS blocks have been zeroed out before data is written into them.





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1. Choose Thin if capacity is your top concern.

2. Choose Eager Zeroed Thick if performance is your top concern.

3. If the VMFS volume is shared by different ESXs, you are advised to choose Eager Zeroed Thick to

prevent faults during VM startup.

5.3.2 Virtual Disk Modes

VMFS supports the following virtual disk modes:

Independent: The disk is not included when a snapshot is created for the VM. The

Independent mode includes the following sub-modes:

− Persistent: The data updates are persistently saved on the virtual disk.

− Non-persistent: The data updates are discarded when the virtual machine is powered

off or the VM snapshot is restored.

Dependent: A snapshot for the virtual disk is created when a snapshot for the VM is

created. In the Dependent mode, the data updates are persistently saved on the virtual

disk.

There is no notable virtual disk performance difference between the two modes. In the

Non-persistent mode, VMware creates the REDO file in the root directory of the VM and all

read operations of the virtual disk are saved in the file. If the VM is powered off or the VM

snapshot is restored, this file is discarded, so this mode seriously affects virtual disk

performance.

The independent mode is the default mode of the system. Do not use the dependent mode

unless otherwise specified.

5.3.3 SCSI Bus Sharing Methods

VMware supports three SCSI bus sharing methods:

None: The virtual disk cannot be shared by VMs.

Virtual: The virtual disk can be shared by the VMs on the same server.

Physical: The virtual disk can be shared by VMs on any server.

Figure 5-6 VMware bus sharing methods





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1. If RDM volumes are used and shared by VM clusters on different servers, you are advised to choose

the Physical mode for SCSI bus.

2. If VMFS volumes are used and are shared by VMs on different servers, you can choose either the

Physical mode or the None mode. Use the None mode only in specific application scenarios. For

details, see Disabling Simultaneous Write Protection Provided by VMFS using the Multi-Writer

Flag.

5.3.4 Configuring Partition Alignment

In Linux or Windows, data on a disk (or LUN) is organized in the legacy Cylinder, Head, and

Sector (CHS) mode. When a partition is created, 63 sectors are reserved on the head to store

the partition structure information and the main boot record, causing storage layers to be out

of alignment and affecting application performance. The VMFS volume improves this storage

method by reserving 64 KB data on the head when being created, but storage layers are still

out of alignment with the data structure in the storage systems.

Figure 5-7shows the storage structures of the VMDK, VMFS, and LUN. When the cluster,

block, and chunk are out of alignment, reading/writing a cluster causes multiple blocks to be

read or written. In the VMFS-5, if clusters and blocks are out of alignment, multiple block

operations may be caused, resulting in read and write operations of more blocks. In the

VMFS-5, the impact on the block layer is negligible, but performance may still get

compromised if the clusters are out of alignment with blocks.

Figure 5-7 Storage structures out of alignment

Cluster ClusterClusterClusterClusterCluster

Block BlockBlock

Chunk ChunkChunk

Block Block

Chunk ChunkChunk

Cluster

VMDK file (NTFS)

VMFS volume

SAN LUN

Attempt to read

one disk

cluster may

cause read of

up to three

SAN chunks.

Remarks: The figure above is from Recommendation for Aligning VMFS Partitions. You are

advised to use the Fdisk command line tool in ESX and Linux and the Diskpart command line

tool in Windows. Configure partition alignment for disks that require partition alignment, and

for details about configuring partition alignment, see Recommendation for Aligning VMFS

Partitions.





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5.4 Suggestion on RDM Configuration

RDM supports two compatibility modes, and the two modes have no notable difference in

performance. Under normal circumstances, you are advised to choose the Physical mode.

Physical compatibility: allows the client to directly access the hardware. The disk is not

included when a snapshot of the client is created.

Virtual compatibility: allows the virtual disk to use the VMware snapshot and other

advanced capabilities.

5.5 Configuring I/O Queue Depth

Because there are limitations on the I/O queue depth on HBA ports, I/O queue depth of VMs,

and I/O queue depth of LUNs, you are advised to perform the following configuration to

improve system performance:

FC HBA: A single path has a maximum I/O queue depth of 32. Run the esxcfg-module

command to configure the HBA driver and set the maximum concurrence.

Virtual machine: A single VM has a maximum I/O queue depth of 32 by default. Modify

the depth by changing the value of the ESX advanced parameter Disk.SchedQuantum

to 64.

Figure 5-8 Adjusting the I/O queue depth of a VM

LUN: A single LUN has a maximum I/O queue depth of 64 by default. Modify the depth by

changing the value of the ESX advanced parameter Disk.SchedQuantum to 256.

Figure 5-9 Modifying the I/O queue depth of a single LUN

A single virtual disk or SCSI controller has a limited I/O queue depth. Create multiple

virtual disks for the VM and use multiple SCSI controllers to increase the utilization ratio

of storage resources.





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5.6 DRS and HA Are Recommended

The VMware DRS enables the intelligent allocation of computing resources, and the VMware

HA ensures the reliability of virtualized environment and service continuity. The VMware

DRS provides three levels of automation:

Manual: The vCenter presents suggestion on virtualization.

Partially automated: VMs are automatically placed on the host and the vCenter presents

suggestion on the migration of the virtual machines.

Fully automated: Based on the resource usage, VMs are automatically placed on the host

and automatically migrated. VMware has five migration thresholds and offers suggestion

on the migration according to the selected threshold.

In DRS Performance and Best Practices, VMware elaborates on how the VMware DRS

improves the performance. Figure 5-10 shows how the two migration levels improve

performance under an undesirable initial deployment of VMs, and Figure 5-11 shows how the

two DRS migration levels improve performance under a fully balanced initial deployment of

VMs.

You are advised to create an ESX cluster with multiple servers and use the VMware DRS

function to dynamically allocate resources. In addition, you are advised to enable the VMware

HA function to ensure service reliability, performance, and continuity in the virtualized

environment.

Figure 5-10 Performance improvement made by DRS under an undesirable initial deployment of

VMs





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Figure 5-11 Performance enhancement made by DRS under a fully balanced initial deployment of

VMs

Remarks: The figures above are from DRS Performance and Best Practices


for Key VMware Applications 6 Summary



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6 Summary

Huawei is committed to providing customers with quality storage products and solutions, and

HUAWEI OceanStor T series embodies this concept. Based on the VMware platform,

HUAWEI OceanStor T series offers comprehensive solutions and best practice with

high-availability, high-performance, and easy management.

Drawing from the key application solutions on the VMware platform, Huawei integrates its

storage systems with VMware vSphere's high availability and easy management features to

offer integrated architecture. This document describes the best practice of the configuration of

Huawei storage systems (based on VMware vSphere) and can serve as a reference for solution

configuration.


for Key VMware Applications A Glossary



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A Glossary

Acronym Full Name

ASM Automated Storage Management

TCO Total Cost of Ownership

IT Information Technology

DBA Database Administrator

OLTP Online Transaction Processing

OLAP On-Line Analysis Processing

RAC Real Application Clusters

OCR Oracle Cluster Registry

AU Allocation Unit

SAS/FC Fibre Channel

LUN Logical Unit Number

RAID Redundant Array of Independent Disks

SAS Serial Attached SCSI

SATA Serial Advanced

SSD solid state disk

SCSI Small Computer System Interface

ERP Enterprise Resource Planning

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