6.5
Table Of Contents
- Using VMware vSphere Replication
- Contents
- About Using VMware vSphere Replication
- Replicating Virtual Machines
- How the Recovery Point Objective Affects Replication Scheduling
- How the 5 Minute Recovery Point Objective Works
- How Retention Policy Works
- Replicating a Virtual Machine and Enabling Multiple Point in Time Instances
- Using vSphere Replication with Virtual SAN Storage
- Using vSphere Replication with vSphere Storage DRS
- How vSphere Replication Synchronizes Data Between vCenter Server Sites During Initial Configuration
- Replicating Virtual Machines Using Replication Seeds
- Replicating a Virtual Machine in a Single vCenter Server Instance
- Best Practices For Using and Configuring vSphere Replication
- Configure Replication for a Single Virtual Machine to vCenter Server
- Configure Replication for Multiple Virtual Machines to vCenter Server
- Move a Replication to a New vSphere Replication Server
- Stop Replicating a Virtual Machine
- Reconfiguring Replications
- Reconfigure Recovery Point Objectives (RPO) in Replications
- Resize the Virtual Machine Disk Files of a Replication that Uses Replication Seeds
- Resize Virtual Machine Disk Files of a Replication that Does Not Use Replication Seeds
- Change the Point in Time Settings of a Replication
- Change the Target Datastore Location of a Replication
- Monitoring and Managing Replications in vSphere Replication
- Performing a Recovery with vSphere Replication
- Troubleshooting vSphere Replication
- Generate vSphere Replication Support Bundle
- vSphere Replication Events and Alarms
- Solutions for Common vSphere Replication Problems
- Error at vService Bindings When Deploying the vSphere Replication Appliance
- OVF Package is Invalid and Cannot be Deployed
- Connection Errors Between vSphere Replication and SQL Server Cannot be Resolved
- Application Quiescing Changes to File System Quiescing During vMotion to an Older Host
- Configuring Replication Fails for Virtual Machines with Two Disks on Different Datastores
- vSphere Replication Service Fails with Unresolved Host Error
- Scalability Problems when Replicating Many Virtual Machines with a Short RPO to a Shared VMFS Datastore on ESXi Server 5.0
- vSphere Replication Sites Appear in the Not Authenticated State
- Error Recovering Virtual Machine in a Single vCenter Server Instance
- vSphere Replication RPO Violations
- vSphere Replication Appliance Extension Cannot Be Deleted
- vSphere Replication Does Not Start After Moving the Host
- Unexpected vSphere Replication Failure Results in a Generic Error
- Reconnecting Sites Fails If One Of the vCenter Servers Has Changed Its IP Address
- Uploading a Valid Certificate to vSphere Replication Results in a Warning
- vSphere Replication Server Registration Takes Several Minutes
- Generating Support Bundles Disrupts vSphere Replication Recovery
- vSphere Replication Operations Take a Long Time to Complete
- vSphere Replication Operations Fail with Authentication Error
- vSphere Replication Does Not Display Incoming Replications When the Source Site is Inaccessible
- vSphere Replication is Inaccessible After Changing vCenter Server Certificate
- vSphere Replication Cannot Establish a Connection to the Hosts
- Anti-virus Agent in Firewall Terminates Virtual Machine Replication
- Initial Full Synchronization of Virtual Machine Files to VMware Virtual SAN Storage Is Slow
- Configuring Replication Fails Because Another Virtual Machine has the Same Instance UUID
- Not Active Replication Status of Virtual Machines
- vSphere Replication Operations Run Slowly as the Number of Replications Increases
- Error at Reconfiguring the vSphere Replication Management Server from the Virtual Appliance Management Interface
- Unable to Establish an SSH Connection to the vSphere Replication Appliance
- The Replication Pauses When You Add a New Disk To the Source VM
- The vSphere Replication Appliance Root File System Switches to Read-only Mode and Login Fails
How RPO and the Retention Policy Combine
To save some of the replica instances that are created during RPO synchronisations, you can configure
vSphere Replication to keep up to 24 instances per replication. The exact instances that
vSphere Replication keeps are determined by applying a specific algorithm. Using this algorithm, the
vSphere Replication Server tries to match each instance to a slot of the retention policy. Instances that do
not match any slot expire and are deleted. If a slot contains more than one instance, the instances that do
not match the retention criteria are also deleted. vSphere Replication always keeps the latest created
instance and it is not taken into account when determining the number of instances to keep.
When the age of the latest instance approaches the RPO interval, vSphere Replication starts creating a
new replica instance. The start time of the sync operation is the time of the new instance. When the sync
operation completes, vSphere Replication assesses the existing replica instances to determine which
ones to keep:
1 The granularity of the retention policy is determined based on the replication settings. For example, if
you configured vSphere Replication to keep 3 instances for the last 1 day, it means that you want to
keep 3 replica instances that are relatively evenly distributed over 24 hours. This equals
approximately 1 instance in a 8-hour interval, or the granularity of this retention policy is 8 hours.
2 The time of the last saved instance is rounded down to the nearest slot time. If the granularity is 8
hours, the slot times are 0:00, 8:00, and 16:00.
3 The instances that are between the nearest slot time and the last saved instance are traversed. Let
us assume that the time of the last saved instance is 10:55. Following our example, the nearest slot
time is 8:00 o'clock. Let us also assume that the RPO is 1 hour, and each sync operation takes 5
minutes to complete. Between 8:00 o'clock and 10:55, the slot contains an 8:55 instance, and a 9:55
instance.
4 The earliest instance that is newer than the nearest slot time is saved, and the rest of the instances in
this slot are deleted, except for the latest created instance that vSphere Replication always keeps.
Following our example, the 8:55 instance is saved, and the 9:55 instance is deleted. The 10:55
instance is the latest created instance, so it is also saved.
5 The slot time is decremented by the granularity of the retention policy and a check is performed for
the earliest instance between the beginning of the current slot and the beginning of the previous slot.
If the slot contains expiring instances, they are deleted.
6 The number of slots that contain saved instances is analyzed. If the number of slots with saved
instances is higher than the number of slots determined by the retention policy, the oldest saved
instance expires and is deleted. The last saved instance is not included in this count. In our example,
if we had an instance saved for the interval 8:00 - 16:00 o'clock of the previous day, that instance
would be deleted.
Using VMware vSphere Replication
VMware, Inc. 8