cvs commit: src MAINTAINERS
phk at phk.freebsd.dk
Tue Aug 17 06:44:07 PDT 2004
In message <20040817132740.GA32139 at freebie.xs4all.nl>, Wilko Bulte writes:
>RAID-3 IIRC uses a dedicated parity disk, and small stripes. I don't think
>it must be bytelevel striping. Just small enough stripes that all disks
>contribute to every I/O
RAID3 differs from RAID5 in that you always access the entire stripe
and never have R/M/W cycles.
Typically the problem is that by doing so you get a RAID3 sectorsize
which is the sum of all non-parity sectors, a 4+1 will give you
4 x 512 = 2048 and 8 + 3 will give you 4k.
Since a lot of filesystems/OS/hardware can only work with 512 byte
sectors, people have hacked around this in various ways and eventually
given up on RAID3.
UFS/FFS works fine with 1k, 2k, 4k and larger sectorsizes and so
RAID3 is a great idea for FreeBSD, and I'd rather use RAID3 than
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