During a discussion about RAID in another context (a Linux newsgroup), I
began thinking about the speeds of the different RAID10 layouts for
different usages. RAID10,far is often the fastest choice for general
use - you get striped reads for large reads, and access times are good
because you can get the data from either disk. The disadvantage is that
writes involve a lot of extra head movement, as you need copies of the
data on two widely separated areas on the each disk. But for general
use, you read a lot more often than you write, so the tradeoff is worth it.
In the discussion we were looking particularly at swap space on RAID.
This is a usage that requires a lot of writing, especially small writes.
Using the RAID10,offset layout should give you most of the benefits of
RAID10,far when it comes to reading - you don't get quite as efficient
block reads for large reads, but you can still do a lot of striping in
the reads. And writes will involve far less head movement, and so
should complete faster.
Has anyone tried this, or done any benchmarking?
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