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Date:      Thu, 21 Sep 2000 07:32:02 -0400 (EDT)
From:      Christopher Stein <>
To:        Robert Watson <rwatson@FreeBSD.ORG>
Cc:        Michael Aronsen <>, "''" <fs@FreeBSD.ORG>
Subject:   Re: Journaling Filesystems in bsd?
Message-ID:  <>
In-Reply-To: <>

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Actually, we described two implementations of journaling within
UFS. CMU built one and Harvard built one. The CMU journaling
UFS uses a system file within the UFS partition for the meta-data
logging. The Harvard journaling UFS uses an auxiliary file system
known as the write-ahead file system (WAFS). "Write-ahead" refering
to the write-ahead logging protocol that maintains the dependencies
between in-place meta-data updates and log writes. This has the
advantage of allowing for the placement of the log on a separate
device - possibly a small, fast disk or even an NVRAM device - and
consequently eliminating data and log head contention.

The file systems were implemented in 4.0-CURRENT.
Craig and I are the main implementors. We are both pretty busy
with grad school stuff (courses, teaching, etc.). However, we
are both keen on getting this out into the community and
this is on the schedule for the near future.


On Thu, 21 Sep 2000, Robert Watson wrote:

> On Thu, 21 Sep 2000, Michael Aronsen wrote:
> > Just wanted to know if there are any projects to get something
> > like reiserfs to FreeBSD? 
> At the June, 2000 USENIX technical conference, a journalled implementation
> of the FFS file system for FreeBSD was described and used in a performance
> comparison with Softupdates.  At the time, it was stated that this
> journalled implementation would be made available to the FreeBSD
> community, although a specific date was not set.  If you're interested in
> the paper, it was by Margo Seltzer, Greg Ganger, Craig Soules, and
> Christopher Stein, and was entitled, ``Journaling Verses Soft Updates:
> Asynchronous Meta-data Protection in File Systems,'' and did a
> comprehensive analysis of the performance and safety implications of
> selecting various forms of file system meta-update protection (sync,
> async, softupdates, async journalling, sync journalling).
> As presumably Kirk would be the vehicle by which the journalling code
> would be incorporated in the base system, and he's currently on vacation,
> the practical answer is probably to sit tight until BSDCon when he
> surfaces again :-). 
>   Robert N M Watson 
> PGP key fingerprint: AF B5 5F FF A6 4A 79 37  ED 5F 55 E9 58 04 6A B1
> TIS Labs at Network Associates, Safeport Network Services
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