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Re: [linux-lvm] HUGE LVM log file...



-- Ragnar Kjørstad <lvm ragnark vestdata no> on 07/18/01 21:23:01 +0200

> On Wed, Jul 18, 2001 at 10:33:21AM +0100, Joe Thornber wrote:
>> This comment is interesting:
>> >> "Seagate uses horizontal mapping with this drive, so that it reaches
>> maximum performance at the beginning of the medium, decreasing at the
>> end of the medium."
>> >> So obviously this varies from drive to drive.
> > You can use zcav from the bonnie++ package
> (http://www.coker.com.au/bonnie++) to find the transfer-rates for your
> drive. I believe finding seek times is a little more tricky since it
> depends on where you're seeking from and that will depend on your
> application.

It is particularly tricky on SCSI's since they remap
bad blocks internally.  You can end up with a butterfly
read due to bad blocks without knowig it.  SCSI's and
the controllers can also silently do scatter/gather on
I/O which helps performance but can cause serious pain for benchmarks.

:-)


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