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Date: Sat, 9 Jan 2010 00:06:59 -1000 (HST)
From: Jeff Roberson <jroberson@jroberson.net>
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To: David Xu <davidxu@freebsd.org>
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Cc: current@freebsd.org
Subject: Re: Help test softupdates journaling (SUJ)
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On Sat, 9 Jan 2010, David Xu wrote:

> Jeff Roberson wrote:
>> Hello,
>> 
>> I have been augmenting softupdates with a small journal that will be 
>> processed in lieu of fsck in the event of a crash.  I have written some 
>> about this project here: http://jeffr_tech.livejournal.com/
>> 
>> For now I need volunteers who will attempt to crash the kernel code.  It 
>> now passes fsx, fsstress, and stress2 on my box for many hours.  pho@ has 
>> been helping me and may still have a bug or two but I need a wider audience 
>> so we can be comfortable with the stability.  In a week or so I will also 
>> provide the checker.  Until then a full fsck is required after a crash.
> Great news, does it also handle crash of recovering procedure ?
> For example, power off during recovering.

The recovery procedure can be safely restarted.  It evaluates the 
filesystem state for each entry in the log.  It doesn't blindly apply 
changes.  It also only does writes at the end once all records have been 
processed.  Since it only modifies inodes and superblocks it doesn't 
require a huge disk cache to make this possible.

Thanks,
Jeff

>
> Regards,
> David Xu
>