Holger,
On Thu, 27 Jul 2000, Holger Kiehl wrote:
> Will this not influence the performance a lot since the head of
> the disk has to walk all over the disk? Thus making comparisons
> practically useless since you never know the state of fragmentation?
I think you've got it exactly right here. Whenever I do a benchmark on a
disk, I follow the following basic plan:
1) Use a freshly formatted disk
2) Disable all but 32M RAM
3) Switch to single-user mode
4) Measure performance at start (maximum) and end (minimum)
5) On large disks (>20G or so), try the first 1G and the last 1G by using
fdisk to create partitions there
6) Use tiotest, NOT bonnie! Try multiple threads (I use 1, 2, 4, 8, 16,
32, 64, 128, 256 threads - this is perhaps excessive!)
I think this provides a pretty good measure of performance, especially how
it degrades under excessive load (256 threads simultaneously trying to rip
data off the disks != good)
If anybody else has any suggestions to add to these, I'd love to hear
them...
> Hope this is not to much off topic.
I think it's pretty important when talking about RAID, since a lot of us
are using it for performance reasons, with the redundancy as an added
bonus.
Regards,
Corin
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