Virtual DR: Disaster Recovery Planning for Virtualized ... · Virtual DR: Disaster Recovery Planning for Virtualized Environments Server virtualization is being touted as a near panacea

Virtual DR: Disaster RecoveryPlanning for Virtualized

Environments

VMware DR considerations

© 2008 Silverton Consulting, Inc. 2

Virtual DR: Disaster Recovery Planningfor Virtualized Environments

VMware DR considerations

Raymond LucchesiPresident

Silverton Consulting, Inc.

[email protected]://www.SilvertonConsulting.com

Abstract

Virtual DR: Disaster Recovery Planningfor Virtualized Environments

Server virtualization is being touted as a near panacea for DRby making it easier than ever to recover servers to a secondarysite. But, just as virtual servers complicate backup procedures,server virtualization has an impact on storage infrastructuresand may require tweaking disaster recovery plans for storagesystems.


Some terminology


VMware DR advantages

• Testability• Hardware independence• P2V, V2V, & V2P• Data encapsulation


DR testability

• VM DR can be tested on otherESX servers in same or remotesite• Easy image copy availability• Easy configuration changes to run VM


Hardware (h/w)independence

• Primary <> DR site h/w• vmkernal isolates and

virtualizes all CPU, networkingand storage h/w interaction• Except Raw Device Mapping (RDM)


P2V, V2V, & V2P• P2V - physical server can be hosted

as a VM on an ESX server via VMconverter, Vconverter, others

• V2V - DR site ESX server h/w canbe different than primary site h/w

• V2P - virtual machine can behosted as a physical server at DRsite


Data encapsulation

• VMware encapsulates all virtualmachine data requirements in fewfiles under one directory• Except RDM data

• File data can be restored to re-starta VM on a remote site ESX server


VMware Datastores

• VMware file systems (VMFS)• DAS• iSCSI• FC storage

• NAS/NFS volumes


VM file system (VMFS)datastore

• VMware cluster file system

LUN0LUN0

LUN0LUN0

LUN0LUN0

LUN7

LUN0LUN0

LUN0LUN0

LUN0LUN0LUN13

LUN0LUN0

LUN0LUN0

LUN0LUN0

LUN0

VMFS0 VMFS1 VMFS2


Files for each VM(.vmx, .vmdk & others)

• File(s) that encapsulate the config,O/S, application, and data for aVirtual Machine (VM)

LUN0LUN0

LUN0LUN0

LUN0LUN0

LUN0

VMFS0

vm1.vmx

vm1.vmdk

vm2.vmx

vm2.vmdk

vm3.vmx

vm3.vmdkESX

VM 1

VM 2

VM 3


Raw Device Mapping (RDM)

Two modes• Virtual compatibility mode

• uses VMFS mapping file• virtualizes physical device I/O

• Physical compatibility mode,• uses VMFS mapping file• I/O directly to physical device bypassing

ESX I/O virtualization• VM snapshots not supported


Using VMware for DRconsiderations

• Removes H/W dependancies• Encapsulates all VM data in few

files• RDM data lone exception


VMware backup alternatives

• Backup s/w agents on VMs• File level backup & restores

• Backup s/w agents on ESX serviceconsole• Image level bacup & restores

• VMware consolidated backup• CDP


VM backup agents

• Backup agents on VM read files• VM backup agent transfers file data to

backup server over LAN• Backup server writes data to backup

target→No .vmdk or .vmx images for DR→Ability to do file level restores→Performance considerations


ESX service console backupagents

• Backup agents on ESX service consolereads .vmdk and .vmx files

• ESX backup agent transfers file data tobackup server over LAN

• Backup server writes data to backuptarget

→ No file level restore→ Performance considerations


VM consolidated backup(VCB)

• “LAN-free” backup of VMs• Suspend VM• Uses VM snapshot to replicate datastores• Catalog’s VM state on snapshot• Resume VM• Snapshots mounted or streamed to VCB proxy• Snapshots backed up to target media via other backup s/w• VCB releases snapshots after backup

• Requires• VCB backup proxy (Windows 2003) server• Other Backup s/w• Shared SAN access to VMFS and snapshots

• Not supported for NAS/NFS datastores or VMFS datastores onDAS or iSCSI


VMware Snapshot

• Copy of disk, memory, cpustate taken point-in-time

• Parent-child relationship• .REDO bitmap files• State of VM?


VCB

Works well for• Offloading ESX server backup

cycles• Image copies of VMs• File level backups for Windows


VCB

Works poorly for• VMs with large .vmdk - need file

level backups• OLTP or always on VMs• RDM physical mode• NAS, iSCSI, DAS based datastores


VCB integrated S/W Tools

• VizionCore VrangerPRO• esXpress• Vmts.net - vmbk.pl• Backup Exec system recovery

option


VMware backupconsiderations

• How you backup VMs impactsDR

• VCB can help DR• For the right VMs


VMware CDP considerations

• VM OS based write splitters providefor VM file protection

• Network and storage array writesplitters support image fileprotection

• Some CDPs support ESX writesplitters via Veritas Volumemanager


VMware local clustering

• DRS for performance optimization• HA for fault tolerance• Both depend on VMotion to migrate

active VMs• Also storage VMotion for local data

migration


VM Dynamic ResourceScheduler (DRS)

Balances performance across definedresource pools

• Uses VMotion to move VMs frombusy to idle ESX servers

• Uses shared access to datastores


VM High Availability (HA)

Local fault tolerant cluster of ESXservers

• Uses heartbeat to detect failure• Uses shared access to VMFS

datastores• Uses VMotion to migrate VMs off

failed ESX servers


VMotion• Running VM quiesced, snapped and terminated• Activates new VM on another ESX sever• Requires

• Shared access to VMFS datastores• Compatible H/W

• VM data stays in place

ESX0

VM 0

VM 1

VM 2

VM 3

ESX1

VM 4

VM 5

VM 6

VM 0


VMware DR alternatives

• Non-RDM DR• RDM DR• VMware Site Recovery Manager• Non-VMware replication-

clustering


Non-RDM VM DRVM data is .vmx, .vmdk(s), & other files• Image copies available• H/W & S/W to run ESX server• Configure ESX server to run VM• Configure datastore(s)• Restore VM files• Start ESX server• Restart VM


RDM VM DR

Same as Non-RDM VM DR but• RDM mapping files in VMFS needed• Physical copy of RDM LUN(s)

required to be backed up andrestored at DR site before VMrestart


VMware Site RecoveryManager (SRM)

• Maps LUNs to VMFS to (.vmdk &.vmx) files

• Automates• Procedures to invoke SAN-LUN replication• Processes to failover to hotsite• Procedures to re-ip networking at hotsite

• Storage supported


SRM replication agents

• Supports VMware SRM API toinitiate, monitor, and terminatestorage replication

• Support for EMC, HDS, IBM,and other storage arrays


Non-VMware replicator-clustering products

• VizionCore Vreplicator• Doubletake System Recovery

Option


Other Cluster software

Operate at VM level only• MSCS• Livelink SUSE• WanSyncHA

Can also operate at ESX server level• Veritas cluster services


Bare metal VM restoreconsiderations

• Can be manual• Can be automated• Through VMware SRM• Through 3rd party software


Storage VMotion

Local data migration• Allows live VM directory migration

to other VMFS datastores• Multi-step process that clones VM

directory and then re-directs allwrites to new datastore

• Uses shared access to all VMFSdatastores


Remote data replicationalternatives

• SAN data mirroring• Storage Virtualization• Replication appliances• Remote CDP


SAN mirroring considerations

• Dedicated networking• Active storage at remote DR site• Types of SAN mirroring

• Synch• Semi-synch• Asynch

• Requires matching storage h/w


VMware SAN mirroringconsiderations

• Insure all LUNs for VMFS datastores aresingle consistency group

• VMFSs being mirrored must contain all.vmdk and .vmx files for VM to berecovered at remote site

• Ophaned VMs• RDM LUNs also need to be mirrored

• Should be included in VMFS consistency group


Storage virtualization

Storage h/w independence• Heterogenous data mirroring• Primary <> DR site storage hardware

• Also provides storage tieringand pooling across subsystems


Replication appliances

• Usually network attached dedicatedh/w providing remote replication

• Can use TCP/IP over WAN for datatransfer

• Support for Asynch mirroring• VMware considerations same as

SAN mirroring


CDP replication appliances

Similar to replication appliancesbut

• Provide any point-in-timerecovery

• Requires write-splitter


Coldsite DR considerations

• Backup data offsite• Could be image or file data

• H/W contracts for guaranteeddelivery timeframes

• S/W agreements for service andlicensing in case of disaster

RTO: 8d..?


Warmsite DR considerations

• Owned DR site or Outsourced DRsite• For outsourced - Sunguard, IBM, HP, etc.

• Data can be at 3rd site or located atDR site• Outsourced sites can be multiple locations

RTO:1d..8d


Hotsite DR considerations

• Asynch replication via s/w,appliance or storage subsystem• Need to replicate datastores and RDM data• S/W support - Vreplicator & Doubletake

SRO• No support for RDM data

• Dedicated networking• Active data replication at DR site

RTO:3h..1d


Mirror site DR considerations

• Dedicated SAN basedreplication• Need to replicate datastores and RDM

data

• Dedicated networking• Active storage at DR site

RTO:0h..3h


For more information

Ray [email protected]

Documents

Virtual DR: Disaster Recovery Planning for Virtualized ... · Virtual DR: Disaster Recovery Planning for Virtualized Environments Server virtualization is being touted as a near panacea