Date: Sun, 25 Jan 2004 13:55:49 -0600 (CST)
From: Eric Sandeen <sandeen@sgi.com>
To: Kelsey Cummings <kgc@sonic.net>
cc: linux-xfs@oss.sgi.com
Subject: Re: [LNX-XFS]  log questions
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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.

> 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.

-Eric