Doing a test to identify the best stipe / block sizes for high end SAN storage.
The test involves setting up LVM raw devices of stripe sizes 128K and beyond - and using dd with block sizes of 128K and beyond.
Issue is :-
Beyond block sizes of 512 K (1024 sectos) - the avgrq-sz does not increase as reported by iostat -x. As if there is a limit. Is this an LVM imposed limit - dm imposed - or even more generic ?
leading upto 1024 sectors avgrq-sz - increases with block size as expected.
Where is the limit ? Is it configurable ?
-JAC
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