Mailinglist Archive: opensuse (818 mails)

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Re: [opensuse] Real World Sata-II disk-to-disk throughput? 77MB/sec is that about right?

On Sun, 25 Sep 2011, David C. Rankin wrote:
Copying video between two Seagate ST31500341AS disks with ext3
filesystems I get about 77.8 MB/sec. Given they are supposed to be
300 MB/sec:

"Is the 77 MB/sec close to the real world max I should expect?"

I understand that the 300 MB/sec is the 'theoretical max'

Those 300 MB/s are what the SATA-II link can theoretically
transfer. The fastest drives max out at about 160 MB/s (linear
read). Remember, due to sheer physical facts those speeds are only
reached in the outermost sectors of the disc. The typical curve over
the capacity looks somewhat like this:

where the innermost speed is only about half of the maximum. Also,
write speeds are usually slower than read speeds. So, depending on
where you read from and write to (and if files need to be fragmented
or can be read and written linearly), 77 MB/s (average) is quite good.


$max = [$a => $b] -> [ $a <= $b ]; ## Simon Cozens
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