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VMFS Thin Volume Management
Hi all,
I'm new to Compellent, so please forgive any ignorance!
I'm looking at ways to maintain the "thinness" of VMFS volumes containing primarily Windows VMs over time. One solution that occurred to me was to use "sdelete" to write zeros to the unused portions of NTFS. The process would go something like this (number in brackets is storage allocated within the array, ignoring any RAID overhead):
- Create a new 100GB VMFS volume (0GB)
- Create a new 10GB "thick" VMDK (0GB)
- Write 5GB of random data into this VMDK (5GB)
- Delete 5GB of data from this VMDK (5GB)
- Run sdelete to write zeros into the unused portions of NTFS (??? GB)
As I understand it, Storage Centre will "catch" my zero writes to the VMFS volume and release the space used within the volume, effectively returning it to the array pool. Or will it only do this when something tells it that it can - i.e. writing zeros is not enough?
Has anyone got any thoughts, recommendations or suggestions around this area?
Many thanks,
Daern.
hallidayr
48 Posts
439
1
Posted January 16th, 2012 09:00
Windows has a utility called Free Space Recovery which can be scripted. I believe it basically works the same way unless you have a direct-mapped LUN with a fancy storage provider set up. In addition to this I think something for vSphere is in the works to cut down on space usage on the Compellent side after, say, a Storage vMotion.