[DRBD-user] sync rate seems low

Monty Taylor mtaylor at mysql.com
Wed Aug 9 02:31:59 CEST 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


When I get back in tomorrow, I'm going to do a disk benchmark as well
as scp'ing a big file. I wasn't showing any significant iowait on
either of the boxes, so I was originally not thinking it was disk -
but I could be wrong.

I'll post when I know how the disk test turns out.

Thanks,
Monty

On 8/8/06, Gary W. Smith <gary at primeexalia.com> wrote:
> But an scp would indicate disk latency as well.  It's great they all
> talk 1gb but can they handle 1gb?  As Clive mentioned, try scp'ing a
> 100mb file and see if you are also getting 8mb/sec.
>
>
>
> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com
> [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Monty Taylor
> Sent: Tuesday, August 08, 2006 4:12 PM
> To: Vampire D
> Cc: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] sync rate seems low
>
> I agree, that's what it seems like. But then I ran iperf on the
> interface and got this:
>
> [  3] local 192.168.0.2 port 32810 connected with 192.168.0.1 port 5001
> [ ID] Interval       Transfer     Bandwidth
> [  3]  0.0-10.0 sec  1.08 GBytes   929 Mbits/sec
>
> Which is more like what I'd expect to see. On the interface. So why is
> DRBD only seeing 100M while the interface can support and is running
> at 1G?
>
> Thanks!
> Monty
>
> On 8/8/06, Vampire D <vampired at gmail.com> wrote:
> >
> > Well first off, I doubt you will be any where near 125M sync rate,
> that's
> > 125MB/s if I am not mistaken.  I run GBit connections and I only have
> a sync
> > rate of around 60M.
> >
> > 2nd, 100Mbit caps at around 12MB/s throughput and 10Mbit is roughly
> 1.2Mb/s
> > so it is definately at 100Mbit.  But 8Mbit isn't all that bad for
> 100Mbit,
> > it is only 2/3rds of the capacity of your network interface, so I
> assume
> > your disk sub system is your bottleneck one way or another.  Try
> benching
> > your drives with timed dd or use some bench tool.
> >
> > With two raptors and Gbit ethernet cross over cabled, I get around
> 56Mb/s
> > but I haven't been able to test the sync rate since the initial sync
> and no
> > one seems to have an answer to easily test that after the drbd is
> > consisitent.
> >
> >
> > On 8/8/06, Monty Taylor <mtaylor at mysql.com> wrote:
> > >
> > Hey all,
> >
> > I'm rolling out a DRBD at the moment and I'm getting much lower
> > initial sync rate than I would expect. I have the two machines
> > connected with crossover cables and the rate set at 125M, but I'm only
> > seeing 8M/sec of transfer rate.
> >
> > I'm sure I'm missing something stupid, but I've rolled DRBD out
> > several times over the past couple of months and never had this
> > problem. Anybody have an idea of something I can check?
> >
> > Thanks,
> > Monty
> > _______________________________________________
> > drbd-user mailing list
> > drbd-user at lists.linbit.com
> > http://lists.linbit.com/mailman/listinfo/drbd-user
> >
> >
> >
> >
> > --
> > "Do the actors on Unsolved Mysteries ever get arrested because they
> look
> > just like the criminal they are playing?"
> >
> > Christopher
> >
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>



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