Input/output error reading USB backup drive on CentOS 6.4
- by Kev
I'm suddenly seeing some strange behaviour on our USB backup drive that doesn't make sense to me:
(2013-10-21 14:58:23 [root@newdc /]$ cd /mnt/backup/
(2013-10-21 14:59:03 [root@newdc backup]$ ls -la
ls: reading directory .: Input/output error
total 0
(2013-10-21 14:59:05 [root@newdc backup]$ df -h /mnt/backup
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 917G 843G 28G 97% /mnt/backup
How is it possible for the OS to know how much is in use, but I can't ls any of it as root? Or more to the point, what problem does this indicate?
/var/log/messages said this:
Oct 21 14:57:54 g5 kernel: EXT4-fs error (device sda1): ext4_journal_start_sb: Detected aborted journal
Oct 21 14:57:54 g5 kernel: EXT4-fs (sda1): Remounting filesystem read-only
But...read-only is something different than 'throw an io error'...
After unmounting to try fsck on it, I had someone on-site look at it, and the drive was not spun up, and had a slow-flashing light, which I believe means it was in a power-suspend mode. So I had them unplug and replug the USB cable, and now (before remounting) it says:
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
/dev/sda1: clean, 2805106/61046784 files, 181934167/244182016 blocks
I then mount it and now ls works and df reports:
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 917G 680G 191G 79% /mnt/backup
What would cause it to go into such a state without being asked to? Why all the weird behaviour, and now it appears to not be corrupt?
