[DRBD-user] sync rate seems low

Tim Hibbard hibbard at research.ohiou.edu
Wed Aug 9 03:13:17 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.


I had super slow sync rates as well over our network.  The servers were 
plugged into the same subnet but I could not get transfer rates faster 
then 12 mb/s

I used a cross over cable and connected them to the second ethernets.  
Then I was geting 80 mb/s.  Must have something to do with our network 
switches or traffic?  Anyways hopes this helps anyone.  Instead of 
waiting 8 hours for a sync I only had to wait 1 hour.

Monty Taylor wrote:
> I couldn't agree more! It would also be really nice to be able to
> query drbd to find out what values the config settings are set to.
>
> Monty
>
> On 8/8/06, Vampire D <vampired at gmail.com> wrote:
>> I really wish there was a interface to tell how fast the drbd devices 
>> are
>> syncing.
>>
>>
>>
>> On 8/8/06, Monty Taylor <mtaylor at mysql.com> wrote:
>> > 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
>> > > >
>> > > _______________________________________________
>> > > 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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