Re: [SLUG] HDD transfer rate

From: Levi Bard (levi@bard.sytes.net)
Date: Mon May 24 2004 - 08:40:31 EDT


>>> Not sure what the "expected" value should be, but for sheer
>>> comparison value here's the output from a quick benchmark of my
>>> ATA-133 drive.
>>>
>>> /dev/hda:
>>> Timing buffer-cache reads: 1012 MB in 2.00 seconds = 505.32 MB/sec
>>> Timing buffered disk reads: 72 MB in 3.07 seconds = 23.43 MB/sec
>>
> Here's a disk in an active raid5 array (note the slower buffer-cache
> reads):
>
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.40 seconds =322.42 MB/sec
> Timing buffered disk reads: 64 MB in 1.21 seconds = 52.76 MB/sec

Hmm, here are my results:

/dev/hda:
 Timing buffer-cache reads: 1904 MB in 2.00 seconds = 952.00 MB/sec
 Timing buffered disk reads: 76 MB in 3.00 seconds = 25.33 MB/sec

The cache read looks ok to me, but should the disk read be better? Ian,
is there anything special about that drive that would make the disk read
so much better than the other two?
Here are my settings:
/dev/hda:
 multcount = 16 (on)
 IO_support = 1 (32-bit)
 unmaskirq = 1 (on)
 using_dma = 1 (on)
 keepsettings = 0 (off)
 readonly = 0 (off)
 readahead = 8 (on)
 geometry = 14596/255/63, sectors = 234493056, start = 0

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