Core technologies used for VM backup, by Eric Siebert, Backup Academy
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Transcript of Core technologies used for VM backup, by Eric Siebert, Backup Academy
Eric SiebertvExpert, Author, Blogger
Blog: http://vsphere-land.com
http://searchvmware.com
Twitter: @ericsiebert
Core Technologies used for Virtual Machine Backup
vExpert nomination
About the speaker
25 year IT industry veteran.
vSphere Land blog: http://vmware-land.com/
Author of popular books
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
Virtual Machine Snapshot Usage
Snapshot
Snapshot
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 serviceRequestor
Application component to work with VSSWriters
Creates the shadow copyProvider
VSS Providers Different types of providers for VSS
Volume Shadow Copy ServiceWriters Requestor
ProviderSQL, Exchange,Active Directory,
Oracle, SharePoint
Backupsoftware
Operatingsystem, storage array or system
provider
Disk Volume
VMware Consolidated Backup (VCB)
VMware File System
LAN
SAN
3rd partyBackup 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
3rd partyBackup Vendors
VCB
VMware Consolidated Backup vStorage API
VMware File System
LAN
SAN
3rd partyBackup Vendors
In vSphere, VCB replaced with Apls Allows 3rd party applications to deliver efficient backups vStorage APls uses to describe various ways to integrate Four categories of vStorage APls
vStorage API Categories
Array-based capabilities
Defer work to storage array
For selected I/O operations
For SAN vendors
Increase storage throughput and failover
Vendors must certify
extensions
vStorage APls for Array Integration (VAAI)
vStorage APls for Multi-pathing (VAMP)
vStorage API Categories
Integrate SRM with array replication
SRA required for storage
Successor to VCB
Address limitations of
VCB
Built into vSphere
Include VCB and new
functionality
Targeted for 3rd party
integration
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
Hash matches that already exist utilize references
Minimal overhead for hashing
Different hash block sizes
Smaller: Maximum dedpulication yet slower backups
Larger: Minimum deduplication yet
faster backups
Look for a VM backup program that provides deduplication
Data Compression
Compression squeezes data into the backup repository
CPU intensive Don’t skimp on resources
8 CPU cores recommended
Multiple compression
levels
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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