On 2/9/2011 11:19 AM, Eric D. Mudama wrote: > For SATA devices, ATA8-ACS2 addresses this through Deterministic Read > After Trim in the DATA SET MANAGEMENT command. Devices can be > indeterminate, determinate with a non-zero pattern (often all-ones) or > determinate all-zero for sectors read after being trimmed. IIRC, it was a word in the IDENTIFY response, not the DATA SET MANAGEMENT command. On 2/9/2011 11:28 AM, Scott E. Armitage wrote: > Who sends this command? If md can assume that determinate mode is > always set, then RAID 1 at least would remain consistent. For RAID 5, > consistency of the parity information depends on the determinate > pattern used and the number of disks. If you used determinate > all-zero, then parity information would always be consistent, but this > is probably not preferable since every TRIM command would incur an > extra write for each bit in each page of the block. The drive tells YOU how its trim behaves; you don't command it. If the drive is deterministic and always returns zeros after TRIM, then mdadm could pass the TRIM down and process it like a write of all zeros, and recompute the parity. If it isn't deterministic, then I don't think there's anything you can do to handle TRIM requests. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
