Re: raid io requests not parallel?

From: Jonathan Baccash
Date: Sun Jul 16 2006 - 12:36:30 EST

Each head has to service 1024 write requests (compared to just 512 read

By that logic, it would take twice as long for my writes to finish.
Why is it taking 4x as long in my parallel test? I don't think any of
the repliers understood my question. What I want to know is, during a
single direct IO write request, I would expect the raid software to
issue the write request to both disks simultaneously. But the evidence
indicates that isn't what is happening. I would expect a raid-1 write
to take about as long to write a single block as a single write to a
single disk (assuming no other disk activity), because I would expect
two writes to happen concurrently.
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