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VMorales1234
2 Posts
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49962
February 28th, 2014 11:00
Compellent reclaim empty/deleted space from a ZFS volume
Our Compellent is being used to host Solaris 10 Virtual Machines. All these VMs are using zfs volumes. The situation we find ourselves in is that deleted space on the zfs volumes is never "released" back to the Compellent.
We have many volumes that are showing on Storage Center as full or nearly full. However, when looking at the volumes from the OS level we can see that the reporting on the Compellent is incorrect (some volumes are only 47% used, etc.)
We know that this is occuring because the Compellent Thin-Provisions everything by default. These volumes at some point had much more data on them than what is currently being used.
Is there a method for having the OS release this space or the Compellent discover the changes to the volumes?
mtanen
118 Posts
1208
0
Posted April 3rd, 2014 08:00
Couple of issues here that make this a unique question -
1) This is a Solaris 10 question
2) It refers to Solaris virtual machines
Couple of clarifications right off the bat for me
Are we talking Solaris Zones or are you running Solaris as VMs inside VMware?
Based on that answer please explain how the LUNS are associated to the VMs, are they RAW or virtualized disks
The short answer to your question is that the ability to clean up high water mark issues is specific to each OS. For Windows, Compellent provides a server agent, for VMware its part of the VAAI additions, for Linux ext4 added notification to the SAN of released blocks.
Before such technologies exists people would do manual copies to "fresh" volumes to reset the high water mark. I think ZFS makes this fairly trivial with their ability to send data between different ZFS entities (or use clones). I am happy to let a ZFS expert detail that process if you need it :)