[DRBD-user] Yet another DRBD Performance question :-)

David Go dglist at ipayroll.co.nz
Tue Apr 12 22:10:09 CEST 2011

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


I am by no means a DRBD expert, but I wonder if your bottleneck is the 2 gig
link.   In the DRBD documentation (I think - maybe it was elsewhere) they note
that performance does not scale with more channel bonded links, and in fact it
actually decreases after 3 or so bonded interfaces, due to the characteristics
of TCP/IP.

I suspect you are seeing really good speeds on multiple threads, but because a
DRBD session is not made up of lots of threads, your performance is maxing out
because of packet ordering.  I believe to get faster performance you may need
to reorganize your network (10 gig interfaces ?)

Cheers,
David Go

On Tue, 12 Apr 2011 19:32:50 +0000, Mark Petersen wrote
> Using drbd 8.3.10 I've seen write performance above ~165 MB/s but I 
> haven't been able to get above ~225 MB/s.  I believe it depends more 
> on PCI, FSB, Memory, QPI, etc. speed/bottlenecks more than the inter-
> connect speeds though, especially when testing with protocol A.
> 
> Mark
> 
> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com [mailto:drbd-user-
> bounces at lists.linbit.com] On Behalf Of Joschi Brauchle Sent: Tuesday,
>  April 12, 2011 11:41 AM To: drbd-user at lists.linbit.com Subject: 
> [DRBD-user] Yet another DRBD Performance question :-)
> 
> Hi all,
> 
> I have yet another DRBD performance question, I know there are tons 
> of them out there and tons of answers+tutorials as well. Thus, I'll 
> keep it really simple and leave out most the technical/configuration 
> detail:
> 
> Scenario: I have a direct 2-gigabit-ethernet link (balance-rr bonded 
> Intel NICs) between the DRBD nodes, achieving 1.97GBits measured 
> with iperf and MTU set to 9200 (which is the max MTU for this NIC). 
> The backing device RAID is capable of 300MB+/s throughput.
> 
> Question: Has anyone ever achieved DRBD (8.3.10) write throughput 
> rates above ~ 165MB/s using a similar 2-gbit-ethernet bonding setup?
> 
> I have found the following post by Lars Ellenberg: 
> http://lists.linbit.com/pipermail/drbd-user/2008-July/009893.html
> He writes about 163 MB/s write speed on the same setup.
> 
> I have probably done all the tweaking the official guides suggest on 
> the ressource config. I have also played around with some TCP 
> tweaking... switched to protocol A, and so on... But no further 
> increase. I measured the DRBD/RAID performance using IOMeter 32kb 
> seq. writes with 1 thread.
> 
> So is ~165MB/s the maximum for DRBD writes on 2-gbit-ethernet?
> 
> Thanks for all your help!
> --
> Dipl.-Ing. Joschi Brauchle, M.Sc.
> 
> Institute for Communications Engineering (LNT)
> Technische Universitaet Muenchen (TUM)
> 80290 Munich, Germany
> 
> Tel (work): +49 89 289-23474
> Fax (work): +49 89 289-23490
> E-mail: joschi.brauchle at tum.de
> Web: http://www.lnt.ei.tum.de/
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David Go
for iPayroll Ltd
----
iPayroll
Phone: 	+64 9 377-1517
Fax: 	+64 9 377-1529




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