bco1505-vmware vsphere replication technical walk-through with engineering_final_us.pdf

Vmware vSphere Replication: Technical Walk-Through with Engineering

Aleksey Pershin, VMware, Inc.

Ken Werneburg, VMware, Inc.

INF-BCO1505

#vmworldinf

2

Disclaimer

This session may contain product features that are

currently under development.

This session/overview of the new technology represents

no commitment from VMware to deliver these features in

any generally available product.

Features are subject to change, and must not be included in

contracts, purchase orders, or sales agreements of any kind.

Technical feasibility and market demand will affect final delivery.

Pricing and packaging for any new technologies or features

discussed or presented have not been determined.

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Agenda

Introduction to vSphere Replication

What’s New in 2012

vSphere Replication and SRM

Configuring VR Replication

VR Internals

Failover and Test

Automated Reprotect and Failback

Summary

4

Agenda





VR Internals

Failover and Test


Summary

5

Introduction to vSphere Replication: Protection for SRM

Replication technology built into the vSphere

platform

Replicates individual VMs

Replicates between

heterogenous datastores

Asynchronous replication with RPO >= 15 min

Released in 2011

Recovery and test are done through SRM

recovery plans

vSphere vSphere

vSphere Replication enables simple

and reliable protection for all Virtual Machines

6

Introduction to vSphere Replication: Architecture

“Protected” Site “Recovery” Site

VRMS VRMS

vSphere Client

SRM Plug-In

vSphere Client

SRM Plug-In

VMFS Storage VMFS

DB DB

SRM Server SRM Server

DB DB

vCenter Server vCenter Server

ESX ESX

VMFS Storage VMFS

ESX ESX ESX

VRA VRA VRA

VRS

DB DB

Replication

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Agenda





VR Internals

Failover and Test


Summary

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vSphere Replication: Protection Built-in to the Platform!

Replication Engine

Delivered with the vSphere

Platform

Bundled with most vSphere

Editions

vSphere vSphere

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New in 2012, Built-in Protection for the Platform

“Standalone” vSphere Replication

• Simple per-VM recovery

Automated reprotect and failback workflows in SRM for VR

Simplified installation and configuration

• Choice to use the embedded database for VRMS

• VRMS and VR Server combined in a single virtual appliance

Application level quiescing

Performance improvements

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Agenda





VR Internals

Failover and Test


Summary

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SVR is now independent of SRM

SVR can replicate within a single vCenter

• SRM will discover and use SVR and its replication

SRM can be installed after SVR

• Gain automation, test recovery, failback, customization, reporting...

Upgrade to SRM

SVR and SRM can coexist

See a more detailed session on using SVR

INF-BCO1436 “vSphere Replication: Use Cases and Implementation Tips”

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vSphere vSphere ESX

vSphere

vSphere

vSphere

VM VM

VR Appliance

vCenter

Protected Site Recovery Site

VR Agent (Further

Appliances for

SRM)

vCenter

NFC Service

vSphere Web UI

vSphere Replication Architecture

VR vSCSI Filter

VM

VR Appliance

13

Agenda




Configuring VR replication

VR Internals

Failover and Test


Summary

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VR replication is configured

per VM in vCenter

Selectable RPO from 15 min up to 24

hours

Selectable destination

datastore (per virtual disk)

15

Configuring VR Replication: Multiple VMs

All VMs will have the same settings (RPO, quiescence, etc.)

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Seeding the Initial Copy to Save Time and Bandwidth

The user can provide the seed for the initial copy

The seed can be delivered through any out-of-band channel

The more recent, the better

The user directs the wizard to the seed files when configuring replication

If using seeds when configuring en masse

The seed files must be placed in a specific way at the target

Refer to the VR user manual for more details

17

Agenda





VR Internals

Failover and Test


Summary

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First, It Does an Initial Full Sync of Source and Target

Compares disk IDs to avoid mismatches

Calculates checksum of all blocks at source and target

Exchanges and compares checksums to determine delta

Replicates all changed blocks necessary to align VMDKs

A B C D E A C

Source Disk Seed Disk tcp/31031

B D E

A B C D E

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After Full Sync, We Switch to Sending the Delta

• Crash consistent if quiescing is turned off

• Allows cross-disk consistency within a VM

• Ongoing I/O not penalized with replication active

• Lightweight snapshots are not the same as VM snapshots (redo logs)

Light-Weight Deltas

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Normally Sends Only Changed Blocks

Switches to delta after first sync

VR Agent tracks all changing blocks via vSCSI filter

Changed blocks replicated as per RPO

A B C D E

Source Disk Target Disk

A C D

tcp/44046

Disks are always consistent

A B C D E AII B CI DI E AII B CI DI E

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Lightweight Snapshots and the LWD Protocol

Writes tracked by vSCSI filter driver

Each replica corresponds to a lightweight snapshot

Bitmap of changed blocks is maintained between replications

During a sync changed blocks are read and sent to the target

LWD protocol – Light Weight Deltas

• Port 31031 – Initial replication traffic

• Port 44046 – Ongoing replication traffic

VR Filter

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Replication Consistency

• VM has a known RPO

Maintains point-in-time consistency

• All disks within a VM treated as an entity

Guarantees cross-disk consistency

• A VMDK will never be corrupt

Every replica is a crash consistent image of the VM

• Improves OS recoverability with VSS

Guest quiescing adds file system consistency

• Flush application writers with VSS

App-level quiescing adds application level consistency

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Protecting Against Network Failures

VR vSCSI filter discards a snapshot only after a sync is completed

VR Server writes each replica into a separate redo log

A redo log is snapshotted only after a sync is completed

Old replicas are collapsed only after a sync is completed

There is always at least one valid replica that corresponds to a

valid lightweight snapshot

Blocks changed LWD Shipped

Redo log

collected

Write

committed to

replica vmdks

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The Replication Scheduler

The scheduler runs in the VR agent on each ESX host

Minimizes RPO violations across all VMs on the host

Tries to minimize the overall bandwidth usage within RPO constraints

Statistical analysis to predict sync durations

Can do “early syncs” in anticipation of large syncs

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Agenda





VR Internals

Failover and test


Summary

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Failover and Test

During a failover, a replica is surfaced as a VM in vCenter

• Replication is automatically stopped

• All replicas are collapsed to avoid a performance penalty at runtime

During a test (SRM only), a snapshot of a replica is surfaced as a VM

• Replication continues to run while test is in progress

• The test VM can write to the disks without affecting the replicas

• After the test the test snapshot is discarded

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Agenda





VR Internals

Failover and Test


Summary

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SRM Allows for Automated Reprotect and Failback

• Reprotect

• Test recovery after reprotect

• Failback

SRM provides additional automation workflows

• Failover shuts down protected VMs and disables power-on

• All VM files are left at the protected site

A successful planned migration is required for reprotect

• All replication settings preserved

• Original VMs used as seeds

• Detects manually configured replications

Reprotect automatically configures VMs for replication in the opposite direction

V

M

D

K1

V

M

D

K2

(VMDK1)

VMDK1 (VMDK2)

VMDK2

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Agenda





VR Internals

Failover and Test


Summary

30

Summary

vSphere Replication provides robust and cost effective replication

More features and improvements coming in 2012

• Automated reprotect and failback in SRM

• Application level quiescing

• Simplified installation

vSphere Replication for SMBs

• Offered with Essentials Plus licenses and above

• Can be upgraded to SRM to provide automation, test, failback

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More Good Stuff!

http://blogs.vmware.com/vSphere/Uptime Twitter @vmKen

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Thank You

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Vmware vSphere Replication: Technical Walk-Through with Engineering

Aleksey Pershin, VMware, Inc.

Ken Werneburg, VMware, Inc.

INF-BCO1505

#vmworldinf

bco1505-vmware vsphere replication technical walk-through with engineering_final_us.pdf

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