Phil Turmel <philip <at> turmel.org> writes: > On 02/16/2015 07:23 AM, Chris wrote: > > .... with raid members that got pulled and are save to > > re-sync. (e.g. after the occasional bad block error that gets remapped by > > the hardrives firmware) > > This should not be part of your concern here, as MD will handle > occassional UREs by reconstructing them and rewriting them on the fly, Phil, thank you for dropping in with this hint. It very likly applies to the disks in the docking station. I searched the mailing list, most hits said to search for the keywords, though. ;-) To understand the issue, I think https://en.wikipedia.org/wiki/Error_recovery_control was good. It would be good if this configuration information could be available there or at https://raid.wiki.kernel.org Cheers, Chris ---- I compiled some snippets from your messages, that could serve as a basis to correction/completion by someone knowledgeable: The default linux controller timeout is 30 seconds. Drives that spend longer than the timeout in recovery will be reset. If they don't respond to the reset (because they're busy in recovery) when the raid tries to write the correct data back to them, they will be kicked out of the array. You *must* set ERC shorter than the timeout, or set the driver timeout longer than the drive's worst-case recovery time. The defaults for desktop drives are *not* suitable for linux software raid. I strongly encourage you to run "smartctl -l scterc /dev/sdX" for each of your drives. For any drive that warns that it doesn't support SCT ERC, set the controller device timeout to 180 like so: echo 180 >/sys/block/sdX/device/timeout If the report says read or write ERC is disabled, run "smartctl -l scterc,70,70 /dev/sdX" to set it to 7.0 seconds. You then set up a boot-time script to do these adjustments at every restart, and make sure you performing regular scrub runs to ...? You might not want that kind of long device timeout, but then you shouldn't use desktop drives in md RAID. Anyone using desktop drives which don't support SCT ERC in md RAID is liable to see long timeouts on the simplest bad sector, and they probably prefer to keep the drive in the array AND have the sector rewritten after reconstruction than have the drive failed out of the array. -- 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
