ufs write safety
David Kewley
kewley at gps.caltech.edu
Wed May 25 22:59:16 UTC 2005
On Wednesday 25 May 2005 15:45, Dave Jones wrote:
> On Wed, May 25, 2005 at 03:38:22PM -0700, David Kewley wrote:
> > Can anyone here provide experience reports or pointers to reports,
> > regarding the safety of Linux's write support for Sun UFS? It is
> > marked as experimental and dangerous, but it appears to have been
> > around since 1998. I'm wondering whether this might be one of
> > those things that works fine but still carries old labels.
>
> It doesn't get any real attention upstream, so I've no particular
> belief that its gotten any more stable than it ever was (wrt writes).
> For this reason, the write support is disabled in Fedora.
>
> > I have several external RAID arrays that up to now have been
> > attached to Sun boxes and formatted with UFS filesystems. I will
> > be attaching these arrays now to a RHEL 4 host.
>
> UFS is also unavailable in RHEL4.
>
> > If I can safely get away with it, I'd prefer to keep writing to
> > the UFS volumes since we're talking about several TB of data.
>
> I certainly wouldn't trust it with data I wanted to keep.
>
> > then I will need to transfer the data to a Linux filesystem with
> > spare TB of space, reformat the external filesystems, and move the
> > data back (or variations on that plan). These are filesystems
> > that several people use for daily work, so I'd rather avoid the
> > copy time if possible.
>
> This is unfortunatly, probably the best way forward.
Thanks *very* much, Dave -- it's good to hear this from someone highly
involved in the kernel. I'll take your advice.
I am using UFS and XFS in RHEL4 by rebuilding the kernel with those
filesystems enabled. The filesystems appear to work fine; I know
others are also using XFS in RHEL4.
I've just now for the first time mounted that Sun UFS volume with this
kernel. I was able to do the one thing I tried -- 'ls' the top-level
directory. :) I had enabled write support in the kernel and mounted it
rw; I'm now going back & re-building that kernel without write support,
per your advice. I could mount ro, but that's not as safe as disabling
writes.
I know that using these filesystems on RHEL4 is neither supported nor
recommended by Red Hat. As an academic site-license customer, however,
I don't get RH support anyway, so I get to make my own choices
appropriate to my risk tolerance. ;)
David
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