[DRBD-user] slow sync speed of 12TB over 10GE
mangoo at wpkg.org
Thu Jan 15 12:27:18 CET 2009
Lars Ellenberg wrote:
> if you cannot get more than 130 MB/sec on top of a ram disk and 10GbE,
> there is something fishy going on,
> and I doubt that drbd can do much about it.
I don't see anything fishy here.
I guess someone is confusing the _read_ speed of a device:
> # hdparm -t /dev/md4
> Timing buffered disk reads: 1102 MB in 3.01 seconds = 366.57 MB/sec
> Timing buffered disk reads: 1040 MB in 3.00 seconds = 346.63 MB/sec
With its _write_ speed:
> [==============>.....] sync'ed: 76.4% (242356/1023804)K
> finish: 0:00:01 speed: 130,240 (130,240) K/sec
How fast can you write on that RAID-6 device (with DRBD sync to the
other node disabled)?
# time dd if=/dev/zero of=/mnt/mountpint/bigfile bs=64k count=100000
# time sync
Also, looking at "iostat -d 1 -k" output in the other terminal while the
writes are going would be interesting.
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