Deduplication ratio explanation

[clickmaster]

Hi there,

could somebody please explain me how deduplication in Virtual SAN works?

I have a 100 GB CSV in a Hyper-V cluster. The volume has 10 GB free space left.
The Virtual SAN device has 73,6 GB with files on the StarWind volume.
The deduplication ratio is 2.27.

I thought that 2.27 means that Virtual SAN has deduplicated the 90 GB data on the CSV with a factor of 227 %.
But I guess I am wrong with this because there are 73,6 GB on the device.

Next thing is: I have a 10 GB device for quorum CSV and it needs 60GB on the Virtual SAN volume.
How can this happen? Why does it need six times more storage than it presents to the Hyper-V hosts?

Every hour StarWind Virtual SAN creates a new SPSPX-file with 132 MB for all thin-provisioned LSFS-devices with deduplication.

Thanks for any help!

[Tarass (Staff)]

Hello Clickmaster,

A few questions to be able to find out the root cause of your issue:
1) Have you created any snapshots on the impacted volume?
2) Have you moved any files to the newly-created / still growing device after the update?

Thank you.

[clickmaster]

Hello Tarass,

1) There are no snapshots.
2) The volume grows without any new files.

At the moment Virtual SAN adds up to four 132 MB SPSPx files per hour and fills up the volume.

[Tarass (Staff)]

Hi Clickmaster,

Thank you very much for your contribution and cooperation.

Recreating LSFS devices on the newest build solves the growing issue.