Writing contigiously to UFS2?
se at FreeBSD.org
Fri Sep 21 05:12:40 PDT 2007
Ivan Voras wrote:
> Fluffles wrote:
>> Even worse: data is being stored at weird locations, so that my energy
>> efficient NAS project becomes crippled. Even with the first 400GB of
>> data, it's storing that on the first 4 disks in my concat configuration,
>> In the past when testing geom_raid5 I've tried to tune newfs
>> parameters so that it would write contiguously but still there were
>> regular 2-phase writes which mean data was not written contiguously. I
>> really dislike this behavior.
> I agree, this is my least favorite aspect of UFS (maybe together with
> nonimplementation of extents), for various reasons. I feel it's time to
> start heavy lobbying for finishing FreeBSD's implementations of XFS and
> raiserfs :)
> (ZFS is not the ultimate solution: 1) replacing UFS monoculture with ZFS
> monoculture will sooner or later yield problems, and 2) sometimes a
> "dumb" unix filesystem is preferred to the "smart" ZFS).
Both XFS and ReiserFS are quite complex compared to UFS definitely
not well described by the term "dumb" ;-)
The FFS paper by McKusick et.al describes the historical allocation
strategy, which was somewhat modified in FreeBSD a few years ago in
order to adapt to modern disk sizes (larger cylinder groups, meaning
it is not a good idea to create each new directory in a new cylinder
The code that implements the block layout strategy is easily found
in the sources and can be modified without too much risk to your
file systems consistency ...
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