How stable is the current driver?

[Richard Garnish]

Bjorn T Johansen wrote:
>Hi.
>
>I am just about to reinstall my Linux system and I was thinking about
>setting up a softward RAID 0 system using a AIC 7890 controller and I was
>just wondering if this is feasible with the current aic7xxx driver?
>Maybe someone can tell how much performance gain one can expect running
>RAID 0?

The AIC7890 is supported in version 5.1.4 of the aic7xxx driver (in kernel
2.0.36) but proper support of Ultra2 drives doesn't work until driver 5.1.6
(the patch against the 2.0.36 kernel is at ftp://ftp.redhat.com/aic/ IIRC).
Version 5.1.4 only runs the drives at 20MB/s, 5.1.6 fixes this so they run
at the correct 80MB/s.  My current RAID 0 setup is only 2 drives (upgrading
to 4 when cash allows) but the performance of the RAID device does seem to
be about 80% of the combined speed of the two drives, which is quite nice
thank you very much :)  I'm hoping that will still be the case when I get to
4 drives, although bus bandwidth starts to become more of an issue at that
point.  CPU usage under heavy load is minimal, but my gut feeling is that a
100MHz system bus is important once the load on the SCSI bus goes up.

Also remember to set up tagged queueing on the drives (assuming they support
it, which AFAIK all Ultra2 drives should) since this becomes rather
important when load is being spread across multiple devices like this.

Richard




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