vnx snapsure

Copyright © 2014 EMC Corporation. All Rights Reserved.

VNX SnapSure

Upon completion of this module, you should be able to:• Describe VNX SnapSure theory and operations• Configure SnapSure• Plan and manage SnapSure

VNX SnapSure 1


VNX SnapSure

This lesson covers the following topics:• Purpose of SnapSure• Key components of SnapSure• SnapSure theory of operations• VNX SnapSure storage usage• Checkpoint scheduling

Lesson 1: VNX SnapSure Theory of Operations

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SnapSure Overview

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• Provides a point-in-time view of a file system known as a “checkpoint”

• Used mostly in backups and file system restores

Purpose of SnapSure

• Live data viewed directly from production file system

• Point-in-time, read-only view from a checkpoint of the production file system (PFS)

Two views of a file system


User’s Views of Data

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biz_proposal

Production File System Checkpoints

Production Wednesday View

Tuesday View

Monday ViewRead-only

Live

Read-only

Read-only

biz_proposal

biz_proposal

biz_proposal


Key Components• Production File System (PFS)• Checkpoint

Logical point-in-time view of data Also known as a “snapshot”

• SavVol Stores original data blocks to preserve the point in time view

• Bitmap Identifies changed data blocks in the PFS

• Blockmap Records the location of data blocks in the SavVol

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Theory of Operation: Part 1 of 7

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• Creating a checkpoint

SavVol

0Bitmap 0 0 0 0 0

Blockmap1PFS SavVol

PFS

A B C D E F

Ckpt 1Data Storage Area



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SavVol

0Bitmap 0 0 0 0 0

Blockmap1PFS SavVol

PFS

A B C D E F

Ckpt 1Data Storage Area

H K

1. Write request is made2. Check the Bitmap value

1

2



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• Writing to the PFS

1. Issue write hold2. Copy original data into SavVol blocks3. Map PFS block to SavVol block4. Update bitmap value to 15. Release write hold

SavVol

0Bitmap 0 1 0 0 1

Blockmap1

B

2 1

E

25

2

3

4PFS SavVol

PFS

A B C D E FCkpt 1

H KHold

1

5



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• Creating a second checkpoint

SavVol

0Bitmap 0 0 0 0 0

Blockmap1

B

2 1

E

25

PFS SavVolBlockmap2PFS SavVol

PFS

A H C D K FCkpt 1

Ckpt 2

• Bitmap is reset to zero values• A new blockmap is created for Ckpt2



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• Writing to the PFS with Ckpt2

SavVol

1Bitmap 1 1 0 0 0

Blockmap1

B

2 1

E

25


126 5

43

A HF

PFS

A H C D K FCkpt 1

Ckpt 2 J L SHold

New

1

2

3

4

5

1. Issue write hold2. Copy data into SavVol3. Update Ckpt2’s blockmap4. Update bitmap values 5. Release write hold



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• Reading from active checkpoint

SavVol

1Bitmap 1 1 0 0 0

Blockmap1

B

2 1

E

25


126 5

43

A HF

3

3

2

1

PFS

J L C D K SCkpt 1

Ckpt 2 A H K FC D

1. Read Bitmap values2. “0” - Retrieve data from PFS3. “1” - Retrieve data from SavVol

Active

Old



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• Reading from old checkpoint

SavVol

1Bitmap 1 1 0 0 0

Blockmap1

B

2 1

E

25


126 5

43

A HF

2

31

PFS

J L C D K S

Ckpt 1

Ckpt 2

A B E FC D

Active

Old

1. Read older checkpoint’s blockmap2. Aggregate oldest values3. Verify active checkpoint’s blockmap for location


SavVol Storage Considerations• All checkpoints of a PFS share the same SavVol

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Automatically-created SavVols

Manually-created SavVols

• Uses the same storage pool as the PFS unless otherwise specified

• If PFS ≥ 20GB then SavVol = 20GB

• If PFS < 20GB and PFS > 64MB then SavVol = PFS size

• If PFS ≤ 64MB then SavVol = 64MB

• A manually-created metavolume is selected during checkpoint creation

• Best practice is to create a SavVol that is 10% of PFS size

• Offers more control on which disks to place the SavVol


SavVol Automatic Extension• Automatic extension is triggered by High Water Mark (HWM)

HWM is 90% by default Will not exceed 20% of total VNX space by default

• SavVol automatic extensions increase in 20 GB increments, or by 10% if SavVol was manually created

• To disable automatic SavVol extension, set HWM to 0% First, SnapSure uses remaining space in SavVol Then, SnapSure will overwrite the oldest checkpoint

• Refresh checkpoints to recycle SavVol storage

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Checkpoint Scheduling Overview

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Automates checkpoint creation and refresh

• Configured via Unisphere or Control Station CLI• Schedules may be on an hourly, daily, weekly, or monthly basis• More than one schedule per PFS is allowed

Proper VNX for File privileges is required

• Read-only: list and view schedules• Modify: change, pause, and resume schedules• Full: create and delete schedules


VNX SnapSure

During this lesson the following topics were covered:• Purpose of SnapSure• Key components of SnapSure• SnapSure theory of operations• VNX SnapSure storage usage• Checkpoint scheduling

Lesson 1: Summary

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VNX SnapSure

This lesson covers the following topics:• Checkpoint creation and verification• Displaying existing checkpoints• Accessing the checkpoint• Configuring checkpoint scheduling

Lesson 2: Configuring SnapSure

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Creating a Checkpoint• Data Protection > Snapshots > File System Checkpoints

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Displaying Checkpoints

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Accessing Checkpoints via CVFS• SnapSure navigation feature for end users to view and restore

checkpoint data without any Administrator involvement CIFS or NFS read-only access

• “.ckpt” is the name of the hidden directory containing checkpoint data Name may be modified via param file

• Naming convention of individual checkpoints yyyy_mm_dd_hh_mm_ss_<Data_Mover_timezone> CVFS names can be changed when remounting the checkpoint

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[root@linux08b student8]# ls -latotal 10323052drwxr-xr-x. 5 root root 1024 Sep 18 22:34 .dr-xr-xr-x. 27 root root 4096 Sep 16 01:43 ..dr-xr-xr-x. 2 root bin 1024 Sep 18 22:25 .etc-rw-r--r--. 1 root root 2857369600 Sep 16 01:48 filename-rw-r--r--. 1 root root 1652555776 Sep 16 01:48 filename2-rw-r--r--. 1 root root 6055657472 Sep 16 01:50 filename3drwxr-xr-x. 2 root root 8192 Sep 11 14:13 lost+found[root@linux08b student8]#[root@linux08b student8]# ls -la .ckpttotal 33dr-xr-xr-x. 2 root root 512 Sep 18 22:47 .drwxr-xr-x. 5 root root 1024 Sep 18 22:34 ..drwxr-xr-x. 5 root root 1024 Sep 16 01:48 2013_09_18_21.46.01_GMTdrwxr-xr-x. 5 root root 1024 Sep 18 21:50 2013_09_18_21.51.29_GMTdrwxr-xr-x. 5 root root 1024 Sep 18 21:56 2013_09_18_21.57.24_GMT

[root@linux08b student8]#

NFS Client Checkpoint Access

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.ckpt directory has to be explicitly specified

Checkpoints appear as directories


NFS Client Checkpoint Access (continued)

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[root@linux08b student8]# cd .ckpt[root@linux08b .ckpt]# ls -ltotal 24drwxr-xr-x. 5 root root 1024 Sep 16 01:48 2013_09_18_21.46.01_GMTdrwxr-xr-x. 5 root root 1024 Sep 18 21:50 2013_09_18_21.51.29_GMTdrwxr-xr-x. 5 root root 1024 Sep 18 21:56 2013_09_18_21.57.24_GMT[root@linux08b .ckpt]#[root@linux08b .ckpt]# cd 2013_09_18_21.46.01_GMT[root@linux08b 2013_09_18_21.46.01_GMT]#[root@linux08b 2013_09_18_21.46.01_GMT]# ls -latotal 10323049drwxr-xr-x. 5 root root 1024 Sep 16 01:48 .dr-xr-xr-x. 2 root root 512 Sep 18 22:42 ..dr-xr-xr-x. 2 root bin 1024 Sep 18 21:25 .etc-rw-r--r--. 1 root root 2857369600 Sep 16 01:48 filename-rw-r--r--. 1 root root 6055657472 Sep 16 01:50 filenames-rw-r--r--. 1 root root 1652555776 Sep 16 01:48 filnamedrwxr-xr-x. 2 root root 8192 Sep 11 14:13 lost+found[root@linux08b 2013_09_18_21.46.01_GMT]#[root@linux08b 2013_09_18_21.46.01_GMT]#


CIFS Client Checkpoint Access • In the address field of Windows Explorer, enter \.ckpt to list the

checkpoints associated with the file system share

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Manually type the path to .ckpt


Accessing Checkpoints via Shadow Copy Client• CIFS clients can also access

checkpoint data via Shadow Copy Client

• Native with Windows 2003 and later OS versions Download available for

Windows 2000 and XP

• Select “Previous Versions” tab on the file system share Properties window

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Displaying Checkpoint Schedules• Data Protection > Snapshots > File System Checkpoints > Schedules Tab

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• Schedule states Active Pending Paused Complete


Creating a Checkpoint Schedule

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Use relative prefix to make script writing easier

Checkpoint names may be assigned


SnapSure Considerations

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Checkpoints depend on PFS and are not originally intended for :

• Disaster recovery• Mirror• High-availability

SnapSure supports 96 read-only checkpoints + 16 writeable• Includes existing checkpoints, checkpoints in a schedule

Avoid creating or scheduling checkpoints during these time periods• 1 to 5 minutes past the hour• 15 minutes of each other in the same schedule or between schedules on the same PFS


VNX SnapSure

During this lesson the following topics were covered:• Checkpoint creation and verification• Displaying existing checkpoints• Accessing the checkpoint• Configuring checkpoint scheduling

Lesson 2: Summary

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VNX SnapSure

This lesson covers the following topics:• Planning checkpoint schedules• Performance considerations

Lesson 3: Planning SnapSure

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Schedule Planning

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Important considerations when planning a checkpoint schedule

• Do not schedule checkpoint operations at the same time as VNX for File database backup

• Do not schedule checkpoints to occur/refresh at the same time

• Missed tasks will be retried

VNX SnapSure


PFS Performance Implications

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•Only reads allowed on the PFS, all write activity will be suspended

Checkpoint Creation

•Only reads allowed on the PFS, all write activity will be suspended

Checkpoint Deletion

•All PFS I/O activity is suspended during restore initialization

Checkpoint Restore

•Write I/O is suspended until original data is copied to the SavVol

Copy On First Write

VNX SnapSure


Client Performance Implications• Refreshing a checkpoint affects user or application access

During a refresh, the checkpoint is deleted and a new one is created with the same name

Checkpoint being refreshed will have all read I/O activity suspended

• If a checkpoint becomes inactive or corrupted, read/write activity on the PFS will continue The PFS does not depend on the checkpoint, but the checkpoint

depends on the PFS

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SavVol Performance and Disk Type• SavVol writes are sequential, while reads are random

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SAS NL-SAS

• Better suited when checkpoints are accessed by heavy read workloads

• Sharing data between users

• Data mining• Testing

• When multiple SavVols will be sharing the same disks

• Very good sequential I/O performance

• Use if checkpoints will be read infrequently

• May be used generally if cost is more important than checkpoint performance

VNX SnapSure


VNX SnapSure

During this lesson the following topics were covered:• Planning checkpoint schedules• Performance considerations

Lesson 3: Summary

34VNX SnapSure


VNX SnapSure

This lesson covers the following topics:• Storage management for checkpoints• Modifying SnapSure schedules• Memory management for checkpoints

Lesson 4: Managing Checkpoints

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Checkpoint Storage Consumption

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• Checkpoint Properties page

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Listing Checkpoints via CLI

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[nasadmin@VNXB ~]$ fs_ckpt fs16 -listid ckpt_name creation_time inuse fullmark total_ ckpt_

savvol_ usage_on used savvol16 Monday 09/18/2013-05:33:52-EDT y 90% 8% 1%17 Tuesday 09/18/2013-05:39:20-EDT y 90% 8% 1%18 Wednesday 09/18/2013-05:45:15-EDT y 90% 8% 1%20 ProdData1 09/24/2013-12:10:00-EDT y 90% 8% 1%21 ProdData2 09/24/2013-13:10:00-EDT y 90% 8% 1%22 ProdData3 09/24/2013-14:10:00-EDT y 90% 8% 1%

Info 26306752329: The value of ckpt_usage_on_savvol for read-only checkpoints may not be consistent with the total_savvol_used.

[nasadmin@VNXB ~]$

VNX SnapSure


Recycling SavVol Storage• One way to create more SavVol space without extension is to

refresh checkpoints

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UnmountCheckpoi

nt

Delete Checkpoint Data

Update Checkpoi

nt to Active

Remount Checkpoi

nt

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Managing Checkpoints

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Modifying Checkpoint Schedules• Schedules may be modified once they are active by accessing their

Properties page

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Memory Requirements for SnapSure• SnapSure allocates up to 1 GB of Data Mover memory for

checkpoint blockmaps 512 MB if DM RAM is less than 4 GB

• Both SnapSure and VNX Replicator require Data Mover memory allocation

• Blockmap entries are paged into Data Mover memory for fast access

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Viewing Blockmap Status

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[nasadmin@VNXB ~]$ server_sysstat server_3 -blockmapserver_3 : total paged in = 0 total paged out = 1 page in rate = 0 page out rate = 0 block map memory quota = 1572864(KB) block map memory consumed = 392(KB)

[nasadmin@VNXB ~]$

VNX SnapSure


VNX SnapSure

During this lesson the following topics were covered:• Storage management for checkpoints• Modifying SnapSure schedules• Memory management for checkpoints

Lesson 4: Summary

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SummaryKey points covered in this module:• SnapSure creates a point-in-time view of a file system that is not

a copy or a mirror image of the original file system• CVFS is a navigation feature that provides NFS and CIFS clients

with read-only access to online, mounted checkpoints from within the PFS namespace

• Checkpoint creation and refreshes can be scheduled on arbitrary, multiple hours of a day, days of a week or days of a month

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vnx snapsure

Documents

typical vnx file system

emc corporation

primary file system

file feature

file metavolume

pfsa production file

snapsure checkpoints

time view of data