Comment 2 for bug 572926

Thank for your report.

The following error appears in dmesg.log
[ 201.805335] ata1: drained 32768 bytes to clear DRQ.
[ 201.870721] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[ 201.870727] ata1.01: ST-ATA: BUSY|DRQ persists on ERR|DF, dev_stat 0x59
[ 201.870733] ata1.01: failed command: READ MULTIPLE
[ 201.870742] ata1.01: cmd c4/00:08:57:7f:46/00:00:00:00:00/f0 tag 0 pio 4096 in
[ 201.870744] res 59/01:08:57:7f:46/00:00:00:00:00/f0 Emask 0x3 (HSM violation)
[ 201.870748] ata1.01: status: { DRDY DRQ ERR }
[ 201.870779] ata1: soft resetting link
[ 202.048324] ata1.00: configured for UDMA/100
[ 202.056552] ata1.01: configured for PIO0
[ 202.056582] sd 0:0:1:0: [sdb] Unhandled sense code
[ 202.056589] sd 0:0:1:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[ 202.056598] sd 0:0:1:0: [sdb] Sense Key : Medium Error [current] [descriptor]
[ 202.056610] Descriptor sense data with sense descriptors (in hex):
[ 202.056616] 72 03 13 00 00 00 00 0c 00 0a 80 00 00 00 00 00
[ 202.056645] 00 46 7f 57
[ 202.056657] sd 0:0:1:0: [sdb] Add. Sense: Address mark not found for data field
[ 202.056668] sd 0:0:1:0: [sdb] CDB: Read(10): 28 00 00 46 7f 57 00 00 08 00
[ 202.056693] end_request: I/O error, dev sdb, sector 4620119
[ 202.056733] ata1: EH complete

This is caused by a hardware problem. You should check your filesystem and storage device. I'm closing this report because it is not a bug with Ubuntu. Don't hesitate to submit any new bug.