[DRBD-user] link aggregate ( bonding module )

Daniel Bourque dbourque at weatherdata.com
Tue Apr 21 20:58:59 CEST 2009


the read speed is actually higher according to hdparm:

[root at box1 bonnie]# hdparm -tT /dev/sdb

/dev/sdb:
 Timing cached reads:   17608 MB in  2.00 seconds = 8813.98 MB/sec
 Timing buffered disk reads:  1124 MB in  3.00 seconds = 374.38 MB/sec

makes me wonder about the accuracy of Bonnie...


Daniel Bourque
Sr. Systems Engineer
WeatherData Service Inc
An Accuweather Company




Tom Brown wrote:
> On Tue, 21 Apr 2009, Daniel Bourque wrote:
>
>> Hi,
>>
>>    My disk writes are benching 2x faster than the GigE dedicated link
>> connecting the DRBD nodes.
>>
>> [root at host1 ]# ./Bonnie -s 1000 -d /var/tmp/
>
> a 1 gig test file? That's probably a bit small. I'd guess you've got 
> at least a gig of memory in the system... and that might be why your 
> write speads are faster than your read speeds? (and why your cpu usage 
> is so high?) I'd make sure your benchmark is valid before you 
> re-engineer your network.
>
> obviously I'm just looking in from the outside, and maybe your test is 
> completely valid. but writes that are faster than reads is unusual 
> unless it is being cached somewhere...
>
> -Tom
>
>
>>
>> Bonnie 1.4: File '/var/tmp//Bonnie.9328', size: 1048576000, volumes: 1
>> Writing with putc()...         done:  50862 kB/s  99.7 %CPU
>> Rewriting...                   done: 732229 kB/s 100.0 %CPU
>> Writing intelligently...       done: 248780 kB/s  54.9 %CPU
>> Reading with getc()...         done:  43119 kB/s  99.9 %CPU
>> Reading intelligently...       done: 2002381 kB/s  99.9 %CPU
>>
>>
>> Thus, the DRBD link creates a bottleneck for disk writes. I would like
>> to use 802.3ad Dynamic link aggregation but looks like DRBD works off 2
>> unidirectional tcp/ip sessions, making it unable to max out the 2 
>> gigE link.
>>
>> Does anyone have any suggestion ( other than buying a pair of 10gigE
>> NICs ) ?
>>
>> thanks
>>
>> -- 
>> Daniel Bourque
>> Sr. Systems Engineer
>> WeatherData Service Inc
>> An Accuweather Company
>>
>>
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>>
>
> ----------------------------------------------------------------------
> tbrown at BareMetal.com   | Courage is doing what you're afraid to do.
> http://BareMetal.com/  | There can be no courage unless you're scared.
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>
>
>



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