Re: io performance...

[Ian Soboroff]

Max Waterman <davidmaxwaterman@xxxxxxxxxxxxxx> writes:

>>> We're still wondering why rd performance is so low - seems to be the
>>> same as a single drive. RAID10 should be the same performance as RAID0
>>> over two drives, shouldn't it?
>>>
>> I think bonnie++ measures accesses to many small files (INN-like
>> simulation) and database accesses.  These are random accesses, which
>> is the worst access pattern for RAID.  Seek time in a RAID equals the
>> longest of all the drives in the RAID, rather than the average.  So
>> bonnie++ is domninated by your seek time.
>
> You think so? I had assumed when bonnie++'s output said 'sequential
> access' that it was the opposite of random, for example (raid0 on 5
> drives) :
>

I could be wrong, I was just reading the information from the bonnie++
website... 

Ian

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