[CentOS] partitioning order and IO performance
timo.schoeler at riscworks.net
Wed Dec 23 18:36:42 UTC 2009
On 12/23/2009 07:29 PM, John R Pierce wrote:
> Ross Walker wrote:
>> I think you might be confusing CAV with CLV of optical drives.
> no, I'm not. most HD's ('green drives' complicate this some) spin at
> a constant RPM, so the rotational latency is the same on the inner and
> outer tracks, an average of 1/2 turn, about 4mS for a 7200 rpm drive,
> and 2mS for a 15000rpm enterprise drive . However, the data rate
> changes. so the outer tracks have more data on them, which is read at a
> higher speed in megabytes/second
That's why in ancient times one was setting up partitions so that the
swap area was the the beginning (mostly the outer tracks of the HD --
never hit a drive that did it the other way round) of the drive.
Try it yourself, get a spare HD and create three partitions on it, two
smaller ones at beginning/end of the drive, the third one filling the
gap between them; install bonnie++ and compare the transfer rates.
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