FSRM soft quotas on dedup-enabled volume

[andy_coster]

Hi,

 

We've got a number of Server 2016 file servers here with dedup enabled, and I'm trying to use FSRM soft quotas on either subfolder or the root of the volumes to simply send an email alert at set thresholds. The problem I have is that the peak usage shows a way higher amount than is actually used on disk.

 

For example, I have a drive of 190GB, which windows shows as having 26GB free. I have enabled both a root level and folder level soft quota with a limit of 189GB, but FSRM 'sees' 358GB used which is 191% of the quota! It's as if FSRM isn't playing with dedup and is reporting on the non-dedup'd size, which shouldn't be the case according to Microsoft:

 

"Creating a hard quota on a volume root folder that also has deduplication enabled is not supported. When a hard quota is present on a volume root, the actual free space on the volume and the quota restricted space on the volume are not the same. This may cause deduplication optimization jobs to fail.

 

Creating a soft quota on a volume root that has deduplication enabled is supported. When FSRM quotas encounter a deduplicated file, File Server Resource Manager accounts for it based on the file’s logical size. Quota usage (including any quota thresholds) does not change when a file is processed by deduplication. All other FSRM quota functionality, including volume-root soft quotas and quotas on subfolders, work normally when using deduplication."

 

What I'm trying to do ought to work, I think. Anyone else come across this, or have any ideas?

 

Thanks

[ChrisMiles]

This is impossible to do using FSRM as it always works with file sizes not size on disk, so a 2GB file uses 2GB of quota even if it dedupes down to nothing. Regardless of what Microsoft may have said, this is how FSRM and dedupe have worked since dedupe was added.

 

I strongly advise against using any quotas or any other FSRM functionality on the root of a volume. Create a folder in which to store everything in order to not interfere with the System Volume Information folder.

Edited June 23, 2017 by ChrisMiles