I've got two test systems here, (IA64 and IA32) and am seeing the same behaviour, but only on the IA32 system. The setup is as follows: both machines are running 2.6.10+udm2, with dual QLA2312 cards (the IA64 has rev 15 and the IA32 system rev 02 cards). Both machines are connected via a brocade fabric to a dual-controller Compaq HSV110. There are 10 luns presented from the HSV110 to each machine. I'm using the following multipath conf for the devices: path_selector "round-robin 0" path_grouping_policy "group_by_serial" getuid_callout "/sbin/scsi_id -g -u -s /block/%n" path_checker "tur" features "1 queue_if_no_path" The active device maps are a single logical volume: hsv110lun1-mysqltest1: 0 209584128 linear consisting of a single multipath physical volume: 3600508b40001417e0001c00001b60000: 0 209715200 multipath 1 0 0 2 2 E 0 2 0 65:240 A 0 8:176 A 0 A 0 2 0 8:16 A 0 65:80 A 1 The filesystem is XFS. To trigger the problem I simply mount the filesystem and wait. There is no IO apart from the filesystem journaling activity. Jan 7 23:49:55 web-4-09 kernel: XFS mounting filesystem dm-11 <No errors reported> Jan 8 01:38:51 web-4-09 kernel: scsi(5): Found in Pending queue pid 468267, State = 6., fcport state=4 jiffies=703298 Jan 8 01:38:51 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 01:39:08 web-4-09 kernel: scsi(5): Found in Pending queue pid 468268, State = 6., fcport state=4 jiffies=707500 Jan 8 01:39:08 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 01:39:25 web-4-09 kernel: scsi(5): Found in Pending queue pid 468269, State = 6., fcport state=4 jiffies=70b768 Jan 8 01:39:25 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 01:39:42 web-4-09 kernel: scsi(5): Found in Pending queue pid 468270, State = 6., fcport state=4 jiffies=70f9d0 Jan 8 01:39:42 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 01:39:59 web-4-09 kernel: scsi(5): Found in Pending queue pid 468271, State = 6., fcport state=4 jiffies=713c38 Jan 8 01:39:59 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 01:40:16 web-4-09 kernel: scsi(5): Found in Pending queue pid 468272, State = 6., fcport state=4 jiffies=717ea0 Jan 8 01:40:16 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. <snip> Jan 8 06:50:50 web-4-09 kernel: scsi(4:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 06:50:51 web-4-09 kernel: scsi(4): Found in Pending queue pid 469587, State = 6., fcport state=4 jiffies=18de3ee Jan 8 06:50:51 web-4-09 kernel: scsi(4:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 06:50:53 web-4-09 kernel: scsi(4): Found in Pending queue pid 469589, State = 6., fcport state=4 jiffies=18debbf Jan 8 06:50:53 web-4-09 kernel: scsi(4:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 06:50:55 web-4-09 kernel: scsi(4): Found in Pending queue pid 469590, State = 6., fcport state=4 jiffies=18df38f Jan 8 06:50:55 web-4-09 kernel: scsi(4:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 06:50:57 web-4-09 kernel: scsi(4): Found in Pending queue pid 469591, State = 6., fcport state=4 jiffies=18dfb5f Jan 8 06:50:57 web-4-09 kernel: scsi(4:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 06:50:57 web-4-09 kernel: SCSI error : <4 0 0 1> return code = 0x20000 Jan 8 06:50:57 web-4-09 kernel: scsi(4:0:2) UNDERRUN status detected 0x15-0x800. <snip> Jan 8 10:36:17 web-4-09 kernel: scsi(5): Found in Pending queue pid 531196, State = 6., fcport state=4 jiffies=25c5130 Jan 8 10:36:17 web-4-09 kernel: scsi(5:0:1) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Jan 8 10:36:17 web-4-09 kernel: SCSI error : <5 0 0 1> return code = 0x20000 Jan 8 10:36:17 web-4-09 kernel: end_request: I/O error, dev sdv, sector 65920 Jan 8 10:36:17 web-4-09 kernel: scsi(5:0:6) UNDERRUN status detected 0x15-0x800. Jan 8 10:36:27 web-4-09 kernel: scsi(5): Found in Pending queue pid 531198, State = 6., fcport state=4 jiffies=25c75af Jan 8 10:36:27 web-4-09 kernel: scsi(5:0:6) qla2x00_done: did_error = 2, comp-scsi= 0x0-0x0. Cheers, Guy Coates -- Dr. Guy Coates, Informatics System Group The Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK Tel: +44 (0)1223 834244 ex 7199