David, > I am wondering if part of the issue is that in my use case, UNMAP and > WRITE SAME zeros result in very different results. With thin > provisioned LUNs, UNMAP requests result in the blocks being freed and > thus reduces the actual size of the LUN allocation on disk. If WRITE > SAME requests are used to zero the blocks, they remain allocated and > thus the real size of the LUN grows to match the allocated size > (effectively thick-provisioning the LUN).
The filer explicitly reported support for WRITE SAME(10/16) with UNMAP. It seems very odd that it would then completely ignore the UNMAP bit and do a regular WRITE SAME. Are you running latest firmware, btw.? In any case. The changes I mentioned are now queued up for 4.12. But it'll obviously take a while for those to trickle into the distributions... -- Martin K. Petersen Oracle Linux Engineering
