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Re: [Xen-users] Using real SSD in domU

> Actually, there was an exchange with James Harper where he confirmed
> Windows GPLPV drivers did not yet have TRIM support, but I do not know
> whether using LVM underneath was related.  He did say he was looking it
> add it to a future release, but I do not know if that release is available 
> yet.

Windows <= 7/2008R2 supports TRIM on AHCI (SATA) devices, but not the SCSI 
equivalent UNMAP for SCSI controllers. GPLPV's xenvbd driver is based on 
storport which is SCSI as far as Windows is concerned. It appears that there 
could be a way with a Windows filter driver to turn higher level IOCTL's into 
SCSI TRIM commands which could allow TRIM on <= 7/2008R2 but I don't really 
have a lot of time to develop yet another driver.

Windows 8/2012 does appear to support UNMAP, it certainly appears to query the 
VPD's that would allow it to detect a thin provisioned device which is 
encouraging. This wouldn't be too much work to implement, but I don't have any 
SSD's to test on at this time.


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