> On Tue, 8 Dec 1998, Leonard Zhang System Administrator ISD RVIB wrote:
> > RAID-1 is disk mirror. DPT is cache with RAID. RAID will increase the
> > disk performance.
> Ugh.. FYI, RAID does not always increase disk performance, and in
> particular RAID-1 is guarunteed not to increase disk performance by it's
What? Join the real world but. Raid-1 doubles read throughput and the
slowdown of writes is negligable.
> very nature (ok, it's conceivable that read performance could be
> increased somewhat, but write performance would, if anything, be decreased
> somewhat). Again, if the cache is actually playing a role in this
> benchmark, then what you are really saying is that IDE is so fast that
> it's 4x faster than DPT's cache memory. Think about that for a minute.
Come off it, when you do disk benchmarks you use a dataset sufficently
large so that the cache doesn't matter. Linux does caching just fine,
DPT's cache is somewhat redundant.
Almost all other raid levels perform worse (like raid 5 where the fastest
write takes 2 reads 1 block XOR and 1 write).
The fastest raid array is a combo of raid-0(striping) and raid-1.
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