Eric SiebertvExpert, Author, Blogger

Blog: http://vsphere-land.com

http://searchvmware.com

Twitter: @ericsiebert

Core Technologies used for Virtual Machine Backup

About the speaker

25 year IT industry veteran.

vSphere Land blog: http://vmware-land.com/Author of popular books

vExpert nomination

Contributor to industry publications

Agenda

Virtual Environment Backup Methods

Virtual Machine Snapshots

Disk-to-Disk Backups

Volume Shadow Copy Service (VSS)

vStorage APIs

Data Deduplication

Data Compression

Virtual Environment Backup Methods

Virtualization introduces more options and flexibility Drastically different than physical infrastructures Traditional backup approach can create bottlenecks

VM disk blocks

Image Level Backups Key difference with VM backups

Image-level backups don’t need OS agents More efficient to backup VMDKs via virtualization layer Image-level backups are complete VM Image-level backups are at block level Empty disk block detection Changed disk blocks

Virtual Machine Snapshots

Writes are redirected

Changes merged into source

VM disks become read-only during a snapshot

Point-in-time picture of a VM

Deleting Virtual Machine Snapshots

Process has changed with different vSphere versions

Helper snapshot is created to hold disk writes

Snapshot 3 disk data file 10 GB

Snapshot 2 disk data file 8 GB

Snapshot 1 disk data file 5 GB

Original VM disk data file 60 GB

Helper Snapshot disk data file 1 GB

Snapshot 2 grows to 18 GB

Snapshot 1 grows to 23 GB

124 3

Deleting Virtual Machine Snapshots

In later vSphere 4.1 & later 4.0 versions, each snapshot is merged directly back into the original disk in turn

Virtual Machine Snapshot Size

>Snapshot3

Snapshot 2

Snapshot 1

Snapshot 4< +

Snapshot files grow over time in 16 MB increments Single snapshot file can never exceed size of source disk Additional changes will change the same block Multiple snapshot can exceed the size of source disk Growth rate determined by disk write activity

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