On Sun, Jan 25, 2004 at 01:55:49PM -0600, Eric Sandeen wrote:
> On Fri, 23 Jan 2004, Kelsey Cummings wrote:
>
> > Another, closely related question: Is is possible to recreate a log on
> > an external device that has been lost?
>
> Sure, just make another device of at least tthe size of the original
> log, and zero it all out. you'd probably want to run repair, depending
> on how you lost the log in the first place.
Presumably extended power failure - or possibly other hardware problems.
> > I'm benchmarking the use of a SSD for the logdevice (results are a bit
> > suprising) and one concern that I have is if the SSD fails, can I create a
> > new log easily for it? I can always make a image of the logdevice with dd,
> > and keep it around as a backup, but that seems a bit strange and I'm not
> > sure that the it would work correctly anyway.
>
> The log is constantly changing, as it is circular. backing it
> up would do you no good; if it dies, you've lost metadata info
> and your fs is inconsistent. You can recover to some extent by
> adding a new device, zeroing it out, and running repair, but this
> is not something you want to do as a matter of course.
The intent was not to get use the image as a 'backup of the log' clearly
that wouldn't be helpful! I was concerned that the log may have some
internal structures or tagging that would require the use of xfs tools and
not just dd, etc.
Thanks!
--
Kelsey Cummings - kgc@xxxxxxxxx sonic.net, inc.
System Administrator 2260 Apollo Way
707.522.1000 (Voice) Santa Rosa, CA 95407
707.547.2199 (Fax) http://www.sonic.net/
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