[DRBD-user] Directly connected GigE ports bonded together no switch
chibi at gol.com
Fri Aug 12 06:58:11 CEST 2011
On Wed, 10 Aug 2011 17:20:12 -0400 (EDT) Jake Smith wrote:
> I tuned my MTU setting on the direct link bond to 9000 and saw a 10%
> improvement on throughput. Negligible on latency though.
> I was getting consistent 180-185MB/s using the throughput testing script
> in the DRBD Users guide with mtu 1500. Iperf was 1.75-1.85Gb/s. After
> changing MTU I get 198-99MB/s consistently and highs at 209-215MB/s.
> Without DRBD my storage controller is delivering 225MB/s so now there's
> almost no cost on the throughput side. Iperf was rock solid at
> 1.97-1.98Gb/s repeatedly.
These numbers match my similar (dual GigE balance-RR replication link)
And if you look back in the archives you can find my numbers for quad GigE
What is more than puzzling to me are these write speeds:
- Initial resync happens at near wire-speed (rate was set to 200MB/s,
ethstats output confirms this speed).
- A makefs (ext4) happens at about the same speed (staring at ethstats).
- A bonnie++ run on the mounted ext4 fs of the DRBD device clocks in at
about 130-150MB/s depending on trailing winds and phase of the moon.
This bonnie result matches what I see from ethstats.
- The same bonnie++ run on the underlying backing device delivers about
So what is different when a FS is mounted as opposed to the raw
(DRBD) device? Where are those 50MB/s hiding or getting lost?
Christian Balzer Network/Systems Engineer
chibi at gol.com Global OnLine Japan/Fusion Communications
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