On Thu, Jul 22, 2010 at 11:14 AM, Miles Nordin <car...@ivy.net> wrote: > reboots. Brandon have you actually set it yourself, or are you just > aggregating forum discussion?
I'm using an older revision of WD10EADS drives that allow TLER to be enabled via WDTLER.EXE. I have not had a drive fail in this environment so I can't speak from personal experience. I'm basing my statement on what I've read in the product specs from the manufacturer and what I've heard about newer revisions of the drives. > AFAICT the feature is useful as a workaround for buggy RAID card > firmware and nothing else. It's a cost differentiator, and you're > swallowing it hook, line and sinker. ERC is part of the ATA-8 spec. WD and Seagate fail to recognize the command on their desktop drives. Hitachi and Samsung implement it. > If you know otherwise please reinform me, but the discussion here so > far doesn't match what I've learned about ZFS and Solaris exception > handling. The idea of ERC is to return an error prior to the timeout. With 60 second timeouts and 5 retries, it could conceivably take 5 minutes for a bad read to fail past the scsi driver. For those 5 minutes, you'll see horrible performance. If the drive returns an error within 7-10 seconds, it would only take 35-50 seconds to fail. ERC allows you to fast-fail with the assumption that you'll correct the error at a higher level. This is true of HW raid cards that offline a disk that is slow to respond as well as ZFS and other software raid mechanisms. The difference is that a fast fail with ZFS relies on ZFS to fix the problem rather than degrading the array. -B -- Brandon High : bh...@freaks.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
