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Old 11-01-2008, 03:23 AM   #1
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Question How to customize and define "i/o block size" for copy test?

Hi everybody,

Are there any methodologies to define "i/o block size" as 1KB, 2KB, 4KB, 16KB, ... for copying any file between internal hard drive and a USB flash for performance test?

Thanks a lot!
Old 11-01-2008, 03:53 AM   #2
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You can try 'dd' and specify the block size. But really, independent of the block size you specify in dd, the filesystem drivers will do their own thing (usually based on the native block size of the device being used). To complicate matters, you also have your buffer sizes (which you *can* change), and this also affects read/write performance.

Now since you mention USB flash, write cycles to flash memory take comparatively HUGE amounts of time. You need a pretty slow processor before your buffer sizes start to affect your write performance to the USB device.
Old 11-01-2008, 05:55 AM   #3
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Thanks a lot, Pinniped, for the hints. I already varied ibs and obs to xK, as the results, througputs are not much different.
Then it would be another point, buffer size, as you mentioned. How and where can I setup this buffer size? Currently I use SuSe Linux 10.0 and 10.3 for the testbeds. Are there any tools for monitoring number of write cycles of flash drive?

Thank you for any further information

Last edited by 3ttt; 11-01-2008 at 12:07 PM.


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