I have a MD raid6 with 5 drives, and every now and then one (random) drive will fail. I've done all sorts of checks, and the drive is actually working fine, so I suspect an issue with the Linux driver and/or SATA controller (onboard). It isn't really relevant to the question, but I'll run through the sata stuff, in case anyone can point out a simple solution to stop this from happening (yes, a new server is on the way, but with budgets etc, that could be some time away. This issue has happened for years, but we are becoming more active with these failures now). 00:0e.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1) 00:0f.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1) 01:07.0 RAID bus controller: Silicon Image, Inc. Adaptec AAR-1210SA SATA HostRAID Controller (rev 02) cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md2 : active raid6 sdh1[5] sdg1[4] sdf1[0] sdd1[6](F) sde1[2] sda1[1] 5860535808 blocks level 6, 64k chunk, algorithm 2 [5/4] [UUU_U] [>....................] recovery = 1.4% (28663240/1953511936) finish=486.5min speed=65938K/sec (As you can see, sdd failed, but the kernel found it again as sdh, so I've re-added it). /dev/md2: Version : 0.90 Creation Time : Fri Aug 11 21:45:20 2006 Raid Level : raid6 Array Size : 5860535808 (5589.04 GiB 6001.19 GB) Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB) Raid Devices : 5 Total Devices : 6 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Fri Sep 7 14:31:10 2012 State : clean, degraded, recovering Active Devices : 4 Working Devices : 5 Failed Devices : 1 Spare Devices : 1 Layout : left-symmetric Chunk Size : 64K Rebuild Status : 1% complete UUID : e6cfbc82:c23e52da:9cb07c6d:11629c30 Events : 0.7762116 Number Major Minor RaidDevice State 0 8 81 0 active sync /dev/sdf1 1 8 1 1 active sync /dev/sda1 2 8 65 2 active sync /dev/sde1 5 8 113 3 spare rebuilding /dev/sdh1 4 8 97 4 active sync /dev/sdg1 6 8 49 - faulty spare Since I know sdh is actually almost up to date, is there some way to re-add it, and only have to sync the portions of the disk which have changed? Thanks, Adam -- Adam Goryachev Website Managers Ph: +61 2 8304 0000 adam@xxxxxxxxxxxxxxxxxxxxxx Fax: +61 2 8304 0001 www.websitemanagers.com.au -- 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