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HD Partitioning

 
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Respected Contributor

Re: HD Partitioning

I've run the same test with only one disk and I think there is a significant difference when it comes to sequential read write. But look for yourselves the bonnie++ output data is attached to the topic.

Some info about the test:
It was done on a DL380G5 with only one 146GB 10K SAS drive.
The server has a BBWC module and the cache setting was set to default.
(75% write adn 25% read if Iâ m not mistaken)
P01.html is the first 10% of the disk
P02.html the last 10.%
file system was ext3.

I used the following command:
Bonnie++ -u root â p /mnt/p01 â q >> p01.csv
Honored Contributor

Re: HD Partitioning

In the old days there were X sectors per track regardless of whether it was on the outer or inner rings of the disk. Today, drive manufacturers optimize around the areal density of the media and cram as many sectors as the media allows into each and every track, basically giving the effect of a constant linear velocity data stream to the head.

The operating system's idea of the geometry of a drive is radically different than its physical layout (query the drive and then compare it to the drive's data sheet). You could think you're writing to a track that's in the inner diameter, and in reality you're writing partial tracks somewhere in the middle, and you actually suffer a performance loss because there's a head position move in there in the middle.

Nothing you can do about it, though--the drive's firmware is in control.