EXT3 filesystem on scsi device becoming readonly

[James Bottomley]

On Mon, 2006-08-28 at 09:31 -0400, Theodore Tso wrote:
> IMHO the right thing is for the device driver to retry for some amount
> of time (maybe measured in seconds or perhaps a single digit number of
> minutes), and in the meantime, pass a signal to the rest of the kernel
> that any process that attempt to write to the filesystem should be
> frozen while we wait for the disk to come back.  

Actually, for this exact case, there's a feature propagating through the
transport classes called the dev loss timer.  It's job, for pluggable
transports like FC, is to allow the user time to unplug and replug
cables before the system declares the device lost and starts erroring
requests (which is what causes the fs to go read only).  Since the
original reporter seemed to be using fibre, it sounds like this would
suit.  Beware:  the dev loss timer shouldn't be much longer than the
SCSI command timeout (say ~30s) or nasty things may happen.

James