Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Thu, Mar 29, 2007 at 11:02:18AM -0700, Jeff Buck wrote:
> OK, I haven't been paying attention which means this is probably a
> stupid question, but is there a reason you're using the raw device
> instead of the drbd device when drbd is loaded? ...and does the drbd
> device show the same degradation?
>
> On Thu, 2007-03-29 at 12:46 -0500, Duane Cox wrote:
> > >
> > > ./dm -a 0 -b 1M -s 3G -y -m -p -o /dev/sdb
> > > 71.87 MB/sec (3221225472 B / 00:42.745236)
how much memory do you have?
did you try to watch some other monitoring tool during these tests?
e.g. "vmstat 1"?
did you check the write cache (hdparm)?
does something change when you use
./dm -a 0 -b 1M -s 3G -y -m -p -x -o /dev/sdb
^^^
(-x: use O_DIRECT...)
((you should not use /dev/sdb when that is configured as lower level
device for drbd))
== drbd disconnected ==
when you write to drbd, and it is disconnected,
drbd needs to update its activity log and dirty bitmap every now and
then, which introduces additional writes, and seeks to the appropriate
drbd meta data locations and back...
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