Eric Siebert vExpert, Author, Blogger Blog: Core Technologies used for Virtual Machine Backup

About the speaker  25 year IT industry veteran. vSphere Land blog: 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 1243

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

Virtual Machine Snapshot Usage Snapshot  Snapshot, by themselves, are not a complete backup solution  Good for short-term recovery points  Left unchecked, snapshot can degrade performance  Snapshot enable image-based backups  Makes VM’s disks read-only for exclusive access at backup  Snapshot deleted at completion of backup process

Disk To Disk Backups Backup Server Primary storage Backup storage  Disk systems increasingly popular as a backup target  Backup repository on disk instead of tape  Most backup applications support disk targets  Backup repository holds deduplicated and compressed data  Target storage can be local or remote: NFS/CIFS/FTP

Disk To Disk Backups  Backup data can be replicated off-site  That data can be offloaded to tape (Disk to Disk to Tape) Backups and restores with disk are much easier and faster Primary storage Backup storage Backup Server Restore Backup

Volume Shadow Copy Service (VSS)  Mechanism for creating consistent copies  Windows-based service, since Windows XP  Block-level within Windows file system  Manages data change and avoids file locking

VSS Components  VSS prepares file system and applications for backup  VSS has several components Initiates request to VSS service Requestor Application component to work with VSS Writers Creates the shadow copy Provider

VSS Providers  Different types of providers for VSS Volume Shadow Copy Service Writers Requestor Provider SQL, Exchange, Active Directory, Oracle, SharePoint Backup software Operating system, storage array or system provider Disk Volume

VMware Consolidated Backup (VCB) VMware File System LAN SAN 3 rd party Backup Vendors 3 rd party Backup Vendors VCB VMware Consolidated Backup  VMare recognized opportunity for more efficiency  VMare Consolidated Backup (VCB) introduced with VI3  VCB was a proxy server to offload backups from VM  VCB mounted virtual disks to then perform image-level backup  Shifted backup overhead to VCB server from VM and host

vStorage APIs VMware File System LAN SAN 3 rd party Backup Vendors 3 rd party Backup Vendors VCB VMware Consolidated Backup vStorage API VMware File System LAN SAN 3 rd party Backup Vendors 3 rd party Backup Vendors  In vSphere, VCB replaced with Apls  Allows 3 rd party applications to deliver efficient backups  vStorage APls uses to describe various ways to integrate  Four categories of vStorage APls

vStorage API Categories vStorage APls for Array Integration (VAAI) vStorage APls for Multi-pathing (VAMP)

vStorage API Categories vStorage APls for Site Recovery Manager (VASRM) vStorage APls for Data Protection (VADP)

vStorage APIs for Data Protection  Two methods for using VADP to back up VMs: Providing backup server directly access VM datastores Using virtual appliance to hot-add VM disk file directly from datastore

Changed Block Tracking  CBT is the standout feature of VADP  What blocks have changed? Best for incremental backups  Allows 3rd party applications to find changes since last backup  Enables faster incremental backups and near CDP Critical technology for baking up VMs Full backup or replication Incremental Changes only

Changed Block Tracking Stores information in special –ctk.vmdk file Fixed length file Size varies by size of VMDK Utilized sequence numbers that inform of changed blocks Enabled by backup applications or advanced VM settings

Data Deduplication  Inline vs. post-processing  Source vs. target  Different chunking methods and hash sizes Deduplication can increase storage efficiency

Data Deduplication  In-line is common, hash calculations are done before blocks are stored in the backup repository Look for a VM backup program that provides deduplication

Data Compression Deduplication and compression dramatically reduce storage requirements

What we covered Virtual Environment Backup Methods Virtual Machine Snapshots Disk-to-Disk Backups Volume Shadow Copy Service (VSS) vStorage APIs Data Deduplication Data Compression

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