Re: [CALL FOR TESTING] Make Ext3 fsck way faster [2.6.24-rc6 -mmpatch]

From: Ric Wheeler
Date: Tue Jan 15 2008 - 10:11:20 EST


Andrew Morton wrote:
I'm wondering about the real value of this change, really.

In any decent environment, people will fsck their ext3 filesystems during
planned downtime, and the benefit of reducing that downtime from 6
hours/machine to 2 hours/machine is probably fairly small, given that there
is no service interruption. (The same applies to desktops and laptops).

Sure, the benefit is not *zero*, but it's small. Much less than it would
be with ext2. I mean, the "avoid unplanned fscks" feature is the whole
reason why ext3 has journalling (and boy is that feature expensive during
normal operation).

So... it's unobvious that the benefit of this feature is worth its risks
and costs?

I actually think that the value of this kind of reduction is huge. We have seen fsck run for days (not just hours) which makes the "restore from backup" versus "fsck" decision favor the tapes...

ric
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