Transcript Slide 1

Core Technologies used
for Virtual Machine
Backup
Eric Siebert
vExpert, Author, Blogger
Blog: http://vsphere-land.com
http://searchvmware.com
Twitter: @ericsiebert
About the speaker
 25 year IT industry veteran.
Author
popular
books
vSphereofLand
blog:
http://vmware-land.com/
Contributor to industry publications
vExpert nomination
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
Image Level Backups
 Key difference with VM backups
VM disk blocks
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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
Point-in-time picture of a VM
VM disks become read-only during a snapshot
Writes are redirected
Changes merged into source
Deleting Virtual Machine Snapshots
Process has changed with different vSphere versions
Helper snapshot is created to hold disk writes
Snapshot 1
grows to 23 GB
4
Helper Snapshot
disk data file 1 GB
3
Original VM disk
data file 60 GB
Snapshot 2
grows to 18 GB
2
Snapshot 1 disk
data file 5 GB
1
Snapshot 2 disk
data file 8 GB
Snapshot 3 disk
data file 10 GB
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
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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
Snapshot 2
<>
Snapshot 1
+
Snapshot 4
Snapshot3
Virtual Machine Snapshot Usage
 Snapshot , by themselves, are not a
complete backup solution
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Good for short-term recovery points
 Left unchecked, snapshot can degrade
performance
 Snapshot enable image-based backups
Snapshot
Snapshot
 Makes VM’s disks read-only for exclusive
access at backup
 Snapshot deleted at completion of backup
process
Snapshot
Disk To Disk Backups
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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
Backup Server
Primary storage
Backup storage
Disk To Disk Backups
Backup
Restore
 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
Backup Server
Primary storage
Backup storage
Volume Shadow Copy Service (VSS)
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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
Requestor
Initiates request to VSS service
Writers
Application component to work with VSS
Provider
Creates the shadow copy
VSS Providers
 Different types of providers for VSS
Writers
SQL, Exchange,
Active Directory,
Oracle, SharePoint
Volume Shadow Copy Service
Requestor
Provider
Backup
software
Disk Volume
Operating
system, storage
array or system
provider
VMware Consolidated Backup (VCB)
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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
VMware Consolidated Backup
LAN
3rd party
Backup
Vendors
VCB
SAN
VMware File System
vStorage APIs
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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
VMware Consolidated Backup
LAN
vStorage API
LAN
3rd party
Backup
Vendors
3rd party
Backup
Vendors
VCB
SAN
SAN
VMware File System
VMware File System
vStorage API Categories
vStorage APls for Array Integration (VAAI)
Array-based
capabilities
Defer work to
storage array
For selected
I/O operations
vStorage APls for Multi-pathing (VAMP)
For SAN
vendors
Increase storage
throughput
and failover
Vendors must
certify
extensions
vStorage API Categories
vStorage APls for Site Recovery Manager (VASRM)
Integrate SRM
with array
replication
SRA required
for storage
vStorage APls for Data Protection (VADP)
Address
limitations of
VCB
Successor
to VCB
Include VCB
and new
functionality
Built into
vSphere
Targeted for
3rd party
integration
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
Deduplication can increase storage efficiency
 Inline vs. post-processing
 Source vs. target
 Different chunking methods and hash sizes
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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