Hi Shivasharan! > For MegaRAID controller we want to support WRITE SAME for non-raid > volumes. Because of host wide "no_write_same = 1" settings, we are > not able to use provision mode.
The no_write_same flag gates whether the WRITE SAME(10/16) commands are used to zero block ranges. It does not influence whether WRITE SAME with the UNMAP bit set is used to deallocate block ranges on devices which support logical block provisioning. > Virtual Disk will not enable WRITE SAME feature providing correct VPD > block limit page. This wasn't always the case. If you want to enable WRITE SAME you'll have to provide some sort of heuristic to avoid breaking things on firmware versions and controllers that predate correct reporting. > Virtual Disk in MegaRAID provides below values in VPD page 0xb0 which > will disable WRITE SAME commands. A value of 0 in Maximum write same length: 0x0 blocks means the maximum length is not reported. It does not mean that WRITE SAME isn't supported. -- Martin K. Petersen Oracle Linux Engineering
