[CentOS] Shrinking a volume group

Kirk Bocek t004 at kbocek.com
Wed Sep 13 15:42:44 UTC 2006

Steve, show your math on how you calculated 58MB/sec from two timed processes. On an
array on one of my servers, I show that the time approximately doubles when running
two processes instead of each by themselves. That still yields about the same throughput.

Also, try running a benchmark like bonnie++:


Steve Bergman wrote:

> # Run two read operations, on different parts of /dev/md1 simultaneously
> # This reads a total of 1GB of data
> time dd if=/dev/md1 bs=4k count=131072 of=/dev/null &
> time dd if=/dev/md1 skip=262144 bs=4k count=131072 of=/dev/null &
> =====
> The results show about 58MB/sec transferred, which is about the same as
> hdparm is showing for each drive individually.
> Running the same thing, but reading the whole 1GB using one dd process
> in the foreground gives identical results.
> Why am I not seeing higher numbers?
> Thanks,
> Steve
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