I/O errors on pendrive - what may cause them? (maybe a bad sector)

Question

When I use a pendrive with Ubuntu, it sometimes disconnects. I looked in syslog and I found I/O error, dev sdb, sector 31159048, so I suppose it's a bad sector. How can I fix it?

Here's a full log of what happens:

Dec 12 09:14:04 puff kernel: [18790.617487] sd 8:0:0:0: [sdb] Attached SCSI removable disk
... and after a while, during a file transfer:
Dec 12 09:15:34 puff kernel: [18880.708328] usb 1-1.5: USB disconnect, device number 9
Dec 12 09:15:34 puff kernel: [18880.718691] sd 8:0:0:0: [sdb] Unhandled error code
Dec 12 09:15:34 puff kernel: [18880.718707] sd 8:0:0:0: [sdb]  Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
Dec 12 09:15:34 puff kernel: [18880.718709] sd 8:0:0:0: [sdb] CDB: Write(10): 2a 00 01 db 73 08 00 00 f0 00
Dec 12 09:15:34 puff kernel: [18880.718714] end_request: I/O error, dev sdb, sector 31159048
Dec 12 09:15:34 puff kernel: [18880.719247] sd 8:0:0:0: [sdb] Unhandled error code
Dec 12 09:15:34 puff kernel: [18880.719249] sd 8:0:0:0: [sdb]  Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
Dec 12 09:15:34 puff kernel: [18880.719250] sd 8:0:0:0: [sdb] CDB: Write(10): 2a 00 01 db 73 f8 00 00 f0 00
Dec 12 09:15:34 puff kernel: [18880.719254] end_request: I/O error, dev sdb, sector 31159288
Dec 12 09:15:35 puff kernel: [18881.010913] usb 1-1.5: new high-speed USB device number 10 using ehci_hcd
Dec 12 09:15:35 puff kernel: [18881.205915] scsi9 : usb-storage 1-1.5:1.0
Dec 12 09:15:35 puff mtp-probe: checking bus 1, device 10: "/sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.5"
Dec 12 09:15:35 puff mtp-probe: bus: 1, device: 10 was not an MTP device
Dec 12 09:15:37 puff kernel: [18883.039242] scsi 9:0:0:0: Direct-Access     JetFlash Transcend 16GB   1100 PQ: 0 ANSI: 0 CCS
Dec 12 09:15:37 puff kernel: [18883.040027] sd 9:0:0:0: Attached scsi generic sg1 type 0
Dec 12 09:15:37 puff kernel: [18883.040601] sd 9:0:0:0: [sdb] 31703040 512-byte logical blocks: (16.2 GB/15.1 GiB)
Dec 12 09:15:37 puff kernel: [18883.042215] sd 9:0:0:0: [sdb] Write Protect is off
Dec 12 09:15:37 puff kernel: [18883.042219] sd 9:0:0:0: [sdb] Mode Sense: 43 00 00 00
Dec 12 09:15:37 puff kernel: [18883.042934] sd 9:0:0:0: [sdb] No Caching mode page present
Dec 12 09:15:37 puff kernel: [18883.042938] sd 9:0:0:0: [sdb] Assuming drive cache: write through
Dec 12 09:15:37 puff kernel: [18883.045835] sd 9:0:0:0: [sdb] No Caching mode page present
Dec 12 09:15:37 puff kernel: [18883.045838] sd 9:0:0:0: [sdb] Assuming drive cache: write through
Dec 12 09:15:37 puff kernel: [18883.046834]  sdb: sdb1
Dec 12 09:15:37 puff kernel: [18883.049582] sd 9:0:0:0: [sdb] No Caching mode page present
Dec 12 09:15:37 puff kernel: [18883.049587] sd 9:0:0:0: [sdb] Assuming drive cache: write through
Dec 12 09:15:37 puff kernel: [18883.049591] sd 9:0:0:0: [sdb] Attached SCSI removable disk

Answer 1

If it's a bad sector, the only way to fix it is to get a new pen drive. It's also possible that the drive connector is bad, in which case you also need a new drive. A third possibility is that the port on your computer is bad, did you try another port? If it's broken on one port, that port is broken. If the drive is broken on more then one PC then the drive is broken.