Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2004-10-05 11:23:53 -0500
\ Todd Denniston:
> Lars Ellenberg wrote:
> >
> > / 2004-10-05 17:59:08 +0200
> > \ Bernd Schubert:
> > > On Tuesday 05 October 2004 17:13, Benoit.Ropartz at alcatel.fr wrote:
> > > > Ok i have tested writes speed during normal operation and i got sames
> > > > results
> > > > with two versions ~ 600 Ko/s.
> > > >
> > > > But why i find difference when syncing is active (30ko=>2ko) ???
> > >
> > > Just read the changelog of 0.7.5, the write speed barrier of 30MB/s has gone
> > > with this version. Probably you are now syncing with the full speed of your
> > > hardware (check the logs or /proc/drbd during the synchronisation to get the
> > > sync speed) and with the previous version only at 30MB/s and so there was l
> > > more capacity left for normal writing operation.
> >
> > right.
> > thanks for answering those questions.
> Just did some looking on the net. What happened to sync-nice (from 0.6.x),
> does it have an upgrade (0.7.x) counterpart?
gone.
currently 0.7 resync does timer based poll. can certainly be improved.
in the long term I want to have more like a
"reserve application bandwidth 10M" instead of "sync rate 5M",
which would just do as best it can, unless there are application writes.
> The reason I ask is that with our setup I found setting sync-max to just under
> the max our hardware would support and sync-nice to 1, got a nice mix of fast
> syncing when everyone is at home, but a machine that responds reasonably fast
> even while syncing during the day.
One thing that all drbd 0.6 users seem to overlook with 0.7 when talking
about the resync speed:
after primary crash,
DRBD 0.6 resyncs THE WHOLE lower level device. ALL 1500 GB, or 4TB, or
what you have. It took HOURS. Days, with certain configurations.
DRBD 0.7 resyncs ONLY THE ACTIVE SET, and you can configure that.
al-extents 257; => ~ 1GB to resync.
al-extents 29; => ~ 120MB to resync.
regardless of the device size.
this takes MINUTES. sometimes seconds.
that is, if YOU are very fast, say you fly with warp 7, and you go
ballistic, and fly via the orbit, you may need HALF AN HOUR to get
from london to sydney, non-stop. typically, using a 747, you need
A FULL DAY minimum, and you need to stop-over to refuel in singapore.
if I walk, not run, from here to next door,
I'm there in 10 SECONDS.
got it?
:)
Lars Ellenberg
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