usb drive keeps umouting itself
I just formatted a new 2TB external drive. I did my first backup on it using dar (850G in total).
The output from dar looks normal.
However, when I try to list the content, there are many input/output errors:
/mnt/backup$ ls -l
ls: cannot access backup_full_20_Apr_2010.68.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.17.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.65.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.66.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.49.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.70.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.69.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.27.dar: Input/output error
ls: cannot access backup_full_20_Apr_2010.48.dar: Input/output error
-rw-r--r-- 1 root root 10G 2010-04-20 22:16 backup_full_20_Apr_2010.42.dar
-rw-r--r-- 1 root root 10G 2010-04-20 22:24 backup_full_20_Apr_2010.43.dar
-rw-r--r-- 1 root root 10G 2010-04-20 22:32 backup_full_20_Apr_2010.44.dar
-rw-r--r-- 1 root root 10G 2010-04-20 22:39 backup_full_20_Apr_2010.45.dar
-????????? ? ? ? ? ? backup_full_20_Apr_2010.46.dar
-????????? ? ? ? ? ? backup_full_20_Apr_2010.47.dar
-????????? ? ? ? ? ? backup_full_20_Apr_2010.48.dar
-????????? ? ? ? ? ? backup_full_20_Apr_2010.49.dar
-rw-r--r-- 1 root root 10G 2010-04-20 17:18 backup_full_20_Apr_2010.4.dar
ls: reading directory .: Input/output error
Apparently, the 'connection' to the HDD was broken... but only partially.
I umounted the device, shut down its power source, then replugged it and remounted it. Now, everything is ok.
It's really strange... and a bit worrisome.
I've been observing the problem: when I mount the usb drive, the 'connection' drops after 30 minutes or so, sometimes more. Apparently, it is still mounted (as seen with df but the KDE4 Device indicator in the taskbar shows it as unmounted) but access to it results in I/O errors. What's really weird is that above, I/O access seemed ok for some files, but not for others in the same directory (I had a konsole already open in that directory before the connection to the drive dropped).
When this happens, I cannot umount as a user (despite having the 'user' flag in fstab). I must umount it as root, then remount it and then everything is fine... for another 30 minutes.
I'm not sure if this is a 'feature' either of the hard drive or of the OS which drops the connection on an external drive which has been idle for too long. If it is, the implementation is sloppy because not consistent. Because of this, it looks more like a bug.
What causes it? Hardware problem? Cable? (the drive is brand new, and I just formatted it).
I notice that I don't suffer from this problem when the drive is actually in use, so the issue is a minor one. I've been checking a large dar backup for several hours, and the process is going on fine.
Since it is a packaged external drive (Seagate 2TB Expansion External Drive), maybe there is some extra hardware to put the drive to sleep when not in use... :-/