This topic has 3 replies, 4 voices, and was last updated February 10, 2020 by Guy A.

Time contrainsts between fail over and commit

Amir B
February 6, 2020 03:51:33 PM

This is a general question on if there are any constraints or recommendations on how long you can leave a VPG in a failover state before clicking commit with reverse protection ?

Viola M
February 7, 2020 03:35:03 AM

Hello Amir,

Viola from Zerto here.

The maximum amount of time you can delay the commit operation is 1440 minutes, which is 24 hours.

Please refer to our admin guidance: http://s3.amazonaws.com/zertodownload_docs/Latest/Zerto%20Virtual%20Manager%20vSphere%20Administration%20Guide.pdf?cb=1581045515

However, we don’t recommend to leave a VPG in before commit, test failover status for too long. As all IO writes during these states are written to a scratch volume, it is important to limit the duration of these states, as when the volume becomes full, the applications can no longer write IOs, which will lead to halting of replication and the inability to edit/remove the VPG.

For your reference: https://www.zrto-dev.com/myzerto/knowledge-base/result-of-leaving-a-vpg-in-the-failover-test-failover-before-commit-or-move-before-commit-states-for-a-long-duration/

Best Regards

Zerto Support

Dipesh P
February 7, 2020 11:01:39 AM

Hi Viola

Thanks for your reply.. what are the scratch volumes and if large enough can we sustain 2-3 hours before committing the VPG ?

Regards

Dipesh

Guy A
February 10, 2020 02:15:53 PM

Hi Dipesh,

Guy from Zerto support here.

A scratch volume is a temporary disk that is attached to the Recovery site VRA during a failover operation.
The idea behind the scratch volume is that all IOs generated during the failover will be written to it.
As Viola stated in her response, it is not recommended to leave a VPG in a pre-commit state for too long because IOs will be constantly written to the scratch volume, which could potentially negatively affect replication.

Please note that 2-3 hours is a reasonable timeframe to wait before committing a failover operation, as it is lower than the maximal delay of 24 hours.

Best regards,
Guy

Tagged: Failover scratch

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