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62440
February 29th, 2016 08:00
SCv2020 and Windows Deduplication
Hi guys, I have an SCv2020 with SCOS 6.6.5 connected via 12 Gbit SAS cables to VMware ESXi 6.0 U1b nodes
I have a Windows 2012 R2 virtual machine where I have enabled Windows native deduplication. The files where heavily duplicated, so I've got an excellent result deduplicating 500 GB to only 30 GB.
The problem is that at the SCOS level I still see 500 GB occupied by data, instead of 30 GB. How can I "clean" the unused data? I have the SCv2020 default Daily Replay Profile attached to this volume.
Many thanks,
Marco
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anhnh77
49 Posts
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March 6th, 2016 00:00
Hi Marco,
1. How you provision the LUN on ESXi and present it to Windows VM?
2. When you do the dedup on Windows (from 500GB to 30GB), is it reflect to ESXi (I mean is there any change in the LUN size on ESXi)
You may refer to the "Compellent free space reclamation" on en.community.dell.com/.../19666365.
Regards,
m.novelli
4 Posts
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March 6th, 2016 08:00
Hello, the LUN is thin provisioned at SCOS level, and thick provisioned at VMware level. I'm NOT using RDM, the LUN is formatted with VMFS
At ESXi level I can't see any change after Windows Deduplication, since the LUN is thick provisioned
Cheers
anhnh77
49 Posts
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March 7th, 2016 22:00
Hi Marco,
You may refer to “Space Recovery on Windows” in the “Dell Enterprise Manager 2015 R3 Administrator’s Guide” document. There is a requirement:
Environment | Supported Configurations for Windows Virtual Machines
------------------------------------------------------------------------------------------------------------------------------------------
VMware | The virtual machine must be running one of the supported Windows Server
| operating systems and configured to access the Storage Center volume in one of
| the following ways
| - Direct map LUN using the Microsoft iSCSI Software Initiator.
| - Raw Device Mappings (RDMs) in physical mode mapped through vSphere.
| (RDMs in virtual mode do not work with Space Recovery.)
Your setup may not match the requirement.
Regards,
m.novelli
4 Posts
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March 8th, 2016 03:00
Well, that's quite a weird config, who still use RDM or direct map LUN with virtual environments? I suppose 1% of VM or less
Marco
775cF01nBb1190993636941
6 Posts
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September 13th, 2018 01:00
The answer is quite simple.
As you thick provisioned the disk in Vmware, Windows won't recognize that it is reclaimable as thin provisioned on the storage side. You can check with Windows defrag tool or "optimize-drive" powershell command.
If you wish to have automatic unmapping then you need to have the Vmware disks as "thin provisioned" (and Vmware virtual machine HW11 or newer) which Windows 2012+ will recognize and attempt to unmap unused blocks back in Vmware, which sends it over to the SAN.
Then there is a caevat with Compellent that has default of 2MB block size that automatic unmapping doesn't work as expected. Manual unmapping on ESX size do work so you might stick to scheduled jobs.