[DRBD-user] Two newbie questions

Bart Coninckx bart.coninckx at telenet.be
Wed Aug 4 20:32:33 CEST 2010


On Wednesday 04 August 2010 18:30:15 Alex Dean wrote:
> On Aug 4, 2010, at 9:12 AM, Steve Thompson wrote:
> > New to DRBD; using it with two Dell PE2900 systems, CentOS 5.5 64-
> > bit. Two questions:
> >
> > (1) I am using dual back-to-back gigabits with mtu=9000 for
> > replication with bonding in balance-rr mode with no issues. The
> > documentation suggests that active-backup mode be used. I'm getting
> > an iperf performance across this link of 1.97 Gbits/sec, and a drbd
> > sync of a single volume gets about 133 MB/sec, which is just a hair
> > quicker than bonnie++ tells me that this file system can block-
> > write. I'm interested in why the active-backup recommendation, and
> > other folks' experiences with bonding.
> 
> I recall seeing a lot of dropped packets when doing drbd replication
> over bonded crossover cables in balance-rr mode.  Things were fine
> under normal circumstances, and drops showed up when I really loaded
> the primary.  active-backup gave me enough throughput, so I switched.
> That was on HP DL380s with Centos 5.5.  I don't recall which ethernet
> driver was in use.
> 
> alex
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So you were basically running with one gigabat NIC at the time ...
I use balance-rr and performance was better during test, admittedly when the 
storage was not stressed. Might try again doing iperf, but I guess results 
will be total bandwidth minus what DRBD uses, which I cannot really tell.

B.


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