storage best practices

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Storage Best Practices

Maor LipchukMarch 2015Senior Software Engineer @ RHEVRed Hatmlipchuk@redhat.com

Irc.oftc.net server on #ovirt channel

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Agenda

● oVirt Storage Domains Overview

● Manual Tiering

● Volume Types

● Single Disk Snapshot

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Storage Domains Types

File Storage Domains

● NFS

● Gluster

● POSIX-Compliant FS

● Local

Block Storage Domains

● Fibre Channel

● ISCSI

● Ceph (oVirt 3.6)

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Manual Tiering

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Manual Tiering

● Introduced in oVirt 3.4

● Maintain different types of Storage Domains in a Data Center

● Feature page: http://www.ovirt.org/Features/Mixed_Types_Data_Center

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Manual Tiering

NFS

iSCSI

FCP

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Manual Tiering

oVirt setup - Manual Tiering

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Manual Tiering - iSCSI

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Manual Tiering - Fibre Channel

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Manual Tiering - NFS

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Manual Tiering

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Manual Tiering - Choose The best Storage

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Manual Tiering

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Volume Types

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Volume Types

● Allocation policy – How should VDSM allocate the storage

● Preallocated - VDSM will try to allocate the space right away

● Sparse/thin provision - Space will be allocated for the volume as needed

● Volume format - How the bits are written to the underlying volume

● RAW - simple raw access

● QCOW2 - file format for disk image files used by QEMU

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Volume Types – Allocation Policy

● Preallocation● improve performance for I/O operations● Wasteful regarding disk space

● Sparse/Thin provisioning● Saving on disk space,● storage is allocated as data is being written to

the file.● Might cause defragmentation ● performance implications

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Volume Types – Volume Format

● QCOW3 (oVirt 3.6)

● QCOW2 - QEMU Copy On Write● File format for disk image files used by QEMU

● The image only represents changes made to an underlying disk image

● Image can contain multiple snapshots of the images history

● Only QCOW2 volumes can be snapshots themselves.

● RAW - Simple raw access

● Has better performance then QCOW2

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Volume Types – Snapshot With QCOW2

SnapshotLV

Base VolumeLV

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Volume Types – Storage Domains

● File Storage Domains● Files thinly provisioned by design● "Preallocation" is achieved by writing zeros

● Block Storage Domains● Thin provisioning - (Transparent to Vdsm) requires defining

the LUNs as sparse on the storage array● Preallocated volumes are simply LVs created with the same

size as the virtual disk

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Volume Types

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Single Disk Snapshot

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Single Disk Snapshot

● Introduced in oVirt 3.4

● Capacity planning & sizing

● Customization of snapshots with regarding to

VM configuration

Disks

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Single Disk Snapshot - LVM

● LVM - logical volume manager for the Linux kernel

● Simple block-level schema for creating virtual block devices

● Manages disk drives and similar mass-storage devices

● Supports up to 500 LVs

● Every disk and a snapshot is a LV

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Single Disk Snapshot – LVM Architecture

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Single Disk Snapshot – oVirt

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Single Disk Snapshot – oVirt

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Questions?

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THANK YOU !

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#ovirt irc.oftc.net

mlipchuk@redhat.com