>> doing a simple performance tests i obtained some very unexpected results: if
>> i issue hdparm -t /dev/md2 i obtain 61 - 65 MB/s while issuing the same test
>> directly on the partitions which compose md2 (/dev/sda3 and /dev/sdb3) i
>> obtain 84 - 87 MB/s. I didn't expect a so big difference between md2 and one
>> of its member. What can cause this difference ?
>
>Maybe their read-ahead settings are different?
>Check out "blockdev --getra /dev/md2", and compare that with the same
>setting of the member disks. You can experiment with changing it by using
>"--setra" as well.
Hi Roman,
thank you for your hint, I verified the read-ahead settings and they are the
same for all the block devices involved in the test: the value is 256 for all
/dev/sd?? and for all /dev/md?
there should be something else which is influencing raid 1 performance.
Have someone of you ever had a similar issue ?
thank you
Marco
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