[nzlug] General software RAID1 query

[Daniel Pittman]

"Roland Hill" <rolandh at ak.planet.gen.nz> writes:

> I've configured software RAID1 on a kubuntu box.

You didn't specify the version, so I shall assume Dapper.

> It's just 2 IDE HDD's in the array, and I put both HDD's on the
> primary IDE channel.
>
> It's bugged me every since, but would I get better read/write
> performance if the HDD's were on separate IDE channels?

Absolutely.  Even simply having a second device on the same IDE channel
can reduce performance by as much as thirty percent, by my measurements,
and having two equally active devices is much worse.

> If so, how hard is it to rebuild the array once I have moved the
> primary slave to the secondary master position.

It isn't.  Ubuntu uses automatic reconstruction of the RAID array based
on the UUID.  It will build the array from the components without any
intervention on your part.

In the absolute worst case, if it doesn't come up at all, simply putting
things back the way they were should resolve the issue.


This isn't true in all cases -- in Dapper -- because it assigns MD
device numbers based on the order it finds the component devices.

In Edgy that will also be fixed, and things will "just work" in all
cases.


Anyway, for what you are trying to do: no problems at all.

Regards,
        Daniel
-- 
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