More on high i/o load wedging Fedora 10

[Chuck Forsberg WA7KGX N2469R]

I reformatted the backup drive with ext2 to see if that made any
difference.  Fedora still wedged during the backup, twice.
The first time it wedged when I was switching screens and
the keyboard went completely dead.  No response to anything,
not even a blink for Caps Lock.  No response to Power button
either.

The second time Fedora wedged I was able to execute some
commands as long as I didn't reference the /u file system
in any way. An ll /tmp command given with the shell in
/u printed the total and then wedged.  The identical command
given from /tmp worked normally.  The only command that
referenced the /u file system in any way that worked was df.

During this time the backup from /y to /b was proceeding
normally.  I was able to suspend the backup with Ctrl-Z.
I waited for disk activity to die down.  I gave a sync command
detached; it did not complete.  The backup responded to a
"fg" command to restart.

Note that /y and root were still working normally despite
being on the same hard drive as the wedged /u file system.

I then issued a reboot command.  It stalled after printing
the first line of its usual sequence.

[caf at omen ~]$ uname -a
Linux omen.com 2.6.27.19-170.2.35.fc10.x86_64 #1 SMP Mon Feb 23 13:00:23 
EST 2009 x86_64 x86_64 x86_64 GNU/Linux

After a hardware reset I mounted the backup drive -o sync.
The backup has been proceeding for the last six or so hours
at a snail's pace, but it has not wedged the system.  The
backup drive is seeking its heart out!  A full backup of
/u /y and /var normally completes in a few hours but
this will take at least an order of magnitude longer, with
much more strain on the physical drive.  This is not
a useful solution.

> /dev/sdb3 on / type ext4 (rw)
> /proc on /proc type proc (rw)
> sysfs on /sys type sysfs (rw)
> devpts on /dev/pts type devpts (rw,gid=5,mode=620)
> /dev/sda1 on /oldroot type ext4 (rw)
> /dev/sdb7 on /x type ext4 (rw)
> /dev/sdb2 on /y type ext4 (rw)
> /dev/sda3 on /v type ext4 (rw)
> /dev/sdb5 on /u type ext4 (rw)
> /dev/sdb1 on /boot type ext2 (rw)
> tmpfs on /dev/shm type tmpfs (rw)
> /dev/sdc3 on /w type ext4 (rw)
> /dev/sdd2 on /z type ext4 (rw)
> none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
> sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
> nfsd on /proc/fs/nfsd type nfsd (rw)
> gvfs-fuse-daemon on /u/caf/.gvfs type fuse.gvfs-fuse-daemon 
> (rw,nosuid,nodev,user=caf)
> /dev/sde1 on /b type ext2 (rw,sync)

-- 
Chuck Forsberg    caf at omen.com   www.omen.com   503-614-0430
Developer of Industrial ZMODEM(Tm) for Embedded Applications
  Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   FAX 629-0665