Extend Refs Deduplication volume beyond 64 TB limit

Question

Is there any downside to extending the volume size of 64 TB Refs formatted drive that has deduplication enabled?

This is a Windows 2019 server that runs Veeam Backup and Replication. We initially set up two Refs formatted drives and made them 64 TB. After creating the drives I was able to extend the volumes to 80 TB and deduplication appears to function properly. However, on the SAN backend the free space is not reclaimed after running "Optimize-Volume -DriveLetter H -ReTrim -Verbose".

Answer 1

Hi，

As far as I know, it's fine to extend Refs volume with data dedup. As for the SAN backend didn't reclaim the free space, it's recommended to involve the storage vendor for Cooperative troubleshooting.

Thanks for your time!
Best Regards,
Anne

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Answer 2

But is it ok to extend an Refs volume with data deduplication enabled on a volume that is 64 TB? Microsoft documentation states that Server 2019 data deduplication supports volumes up to 64 TB. However, if create a 64 TB volume and enable deduplication it is possible to extend the volume size later. Is this okay?

Answer 3

Hi，

I researched but didn't find confirmed information about it. As far as I'm concerned, we may extend the 64TB volume, while the extended space may not have dedup.

If you would like to get definite information, I would suggest you open a case with MS for confimation.

Below is the link to open case with MS:

https://support.microsoft.com/en-us/gp/customer-service-phone-numbers

Thanks for your time!
Best Regards,
Anne

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