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Re: Software RAID and ext3 problem

-- Matthew Sackman <matthew sackman co uk>

The ext2fs blocksize severely influences the performance of the
filesystem. You should always use 4KBblock size on any filesystem
larger than a few hundred megabytes, unless you store a very large
number of very small files on it.

I've been using Software RAID 5 on ext3 for some time (even experimented
with it across enbd which was fun) without problems - but have always
followed the advice in the HOWTO to the letter.

Suggest using either 4 drives x 1K chunk (4k stripe) or 8 drives x 1b chunk (also 4k stripe) and mkfs w/ -b4096.

The 8 drive setup gives better caching performance and
handles streaming output on high-speed (80 or 160MB)
setups but requires high-end cards to keep the scsi
chain from getting saturated. 4 drive setups are more
common simply because the cables that come with most
cards have 4 connectors :-)

Steven Lembark                               2930 W. Palmer
Workhorse Computing                       Chicago, IL 60647
                                           +1 800 762 1582

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