Re: [Jfs-discussion] Detecting when device has been remounted read-only from userspace

[William M. <bm...@us...>]

Shaggy wrote on 05/10/2007 11:36:14 AM:

> On Thu, 2007-05-10 at 09:57 -0400, Daniel Drake wrote:
> > Hi,
> > 
> > Occasionally, JFS detects filesystem corruption during use and and
> > remounts the filesystem read-only. (the corruption is probably 
warranted
> > for, e.g. unexpected power loss happened some time previously)
> 
> jfs really should recover cleanly after a power loss, but caching by the
> disk drives can undermine the journal's integrity.  There may be some
> undiscovered bugs as well.  If there are no i/o errors on the device,
> file-system corruption should be a pretty rare occurrence.
> 
> > Is there a clean way to detect when this happens from userspace, other
> > than checking every single I/O operation? In our case, we'd like to 
pop
> > up a warning and recommend a reboot.
> 
> jfs prints a message to the system log when this happens, so maybe you
> could somehow monitor that?  The message contains "remounting filesystem
> as read-only".

There are a couple of tools like swatch that will watch /var/log/messages 
and then take actions. 

And you probably don't need to reboot. You can:
fsck /home
mount -o remount,rw /home

Bill