Есть диск WD10EARS-00MVWB0. Наблюдаются невероятные тормоза при обращении к нему.

Jan 24 23:23:21 xen1 kernel: [  985.137974] ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
Jan 24 23:23:21 xen1 kernel: [  985.137982] ata6.00: failed command: READ DMA EXT
Jan 24 23:23:21 xen1 kernel: [  985.137992] ata6.00: cmd 25/00:c8:a0:5e:4a/00:03:68:00:00/e0 tag 0 dma 495616 in
Jan 24 23:23:21 xen1 kernel: [  985.137994]          res ff/ff:ff:ff:ff:ff/ff:ff:ff:ff:ff/ff Emask 0x2 (HSM violation)
Jan 24 23:23:21 xen1 kernel: [  985.137998] ata6.00: status: { Busy }
Jan 24 23:23:21 xen1 kernel: [  985.138002] ata6.00: error: { ICRC UNC IDNF ABRT }
Jan 24 23:23:21 xen1 kernel: [  985.138018] ata6: hard resetting link
Jan 24 23:23:21 xen1 kernel: [  985.455992] ata6: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
Jan 24 23:23:21 xen1 kernel: [  985.476458] ata6.00: configured for UDMA/100
Jan 24 23:23:21 xen1 kernel: [  985.476535] ata6: EH complete

Jan 24 23:35:23 xen1 kernel: [ 1707.586207] ata6: lost interrupt (Status 0x50)
Jan 24 23:35:23 xen1 kernel: [ 1707.586278] sd 5:0:0:0: [sdc] Unhandled error code
Jan 24 23:35:23 xen1 kernel: [ 1707.586282] sd 5:0:0:0: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_TIMEOUT
Jan 24 23:35:23 xen1 kernel: [ 1707.586286] sd 5:0:0:0: [sdc] CDB: Read(10): 28 00 6a d8 8b 30 00 04 00 00
Jan 24 23:35:23 xen1 kernel: [ 1707.586298] end_request: I/O error, dev sdc, sector 1792576304
Jan 24 23:36:24 xen1 kernel: [ 1768.576997] ata6: lost interrupt (Status 0x50)
Jan 24 23:36:24 xen1 kernel: [ 1768.577085] sd 5:0:0:0: [sdc] Unhandled error code
Jan 24 23:36:24 xen1 kernel: [ 1768.577090] sd 5:0:0:0: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_TIMEOUT
Jan 24 23:36:24 xen1 kernel: [ 1768.577097] sd 5:0:0:0: [sdc] CDB: Read(10): 28 00 6a d8 8f 30 00 04 00 00
Jan 24 23:36:24 xen1 kernel: [ 1768.577112] end_request: I/O error, dev sdc, sector 1792577328

Выяснилось что из-за idle3=8 сек – через 8 сек. неактивности происходила парковка. При помощи утилиты wdidle3 была отменена парковка.
http://habrahabr.ru/blogs/sysadm/106273/ – WD Green Caviar + Linux = убей свой диск!