[PARPORT] Details on corruption of superblock on Avatar Shark 250

Kevin Fisher (kfisher@rim.net)
Wed, 10 Dec 1997 08:51:40 -0500

Ok, I've taken some time to do some experimentation with my Shark drive
under Linux, and I'm coming to the conclusion the problem isn't with
my hardware.

I posted previously about how my ext2-formatted shark drive was getting
the superblock corrupted under Linux...well, I've managed to duplicate
the problem and how it is caused.

First let me say I've done this under redhat 4.2 and now redhat 5.0
(which I just upgraded to last night :), kernels 2.0.18 and 2.0.31
(I think!)

Okay, yesterday I came home from work around 3:30 to pick something up.
On a whim, I booted my linux machine, mounted one of my ext2 shark
disks, and left. When I returned around 6:30pm, I unmounted the shark
drive, and tried to remount--bang, the superblock was gone again.

This morning I tried something else...I mounted my shark drive and left
it mounted for maybe 10-15 minutes. When I ran 'umount /dev/epa1', and then
re-mounted the drive, AGAIN the superblock was trashed.

There is one common thread here...when I run umount /dev/epa1 on a drive
that has been sitting idle for a while, the umount doesn't happen right
away..I'm not sure what the hardware internals of the Shark drive are, but
it seems that it has to 'spin up' again to unmount (at least, that's what
it sounds like). This causes a momentary delay in the unmounting. Whenever
this happens, the superblock is trashed.

I've tried mounting/unmounting many times...whenever the drive isn't in this
'spun down' state, the disk is unmounted cleanly. Only when there is this
spin-up (or whatever it is) delay does the superblock get munched.

Fortunately, fsck can fix it every time (so far!).

When I attempt to mount a 'munched' superblock disk, the syslog only says

Dec 4 13:08:03 avatar kernel: VFS: Can't find an ext2 filesystem on dev 3f:01.
Dec 4 13:08:18 avatar kernel: VFS: Can't find an ext2 filesystem on dev 3f:01.

There are no ep: errors that I could see within the syslog.

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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:17:10 EST