[DRBD-user] Two newbie questions

Alex Dean alex at crackpot.org
Wed Aug 4 18:30:15 CEST 2010


On Aug 4, 2010, at 9:12 AM, Steve Thompson wrote:

> New to DRBD; using it with two Dell PE2900 systems, CentOS 5.5 64- 
> bit. Two questions:
>
> (1) I am using dual back-to-back gigabits with mtu=9000 for  
> replication with bonding in balance-rr mode with no issues. The  
> documentation suggests that active-backup mode be used. I'm getting  
> an iperf performance across this link of 1.97 Gbits/sec, and a drbd  
> sync of a single volume gets about 133 MB/sec, which is just a hair  
> quicker than bonnie++ tells me that this file system can block- 
> write. I'm interested in why the active-backup recommendation, and  
> other folks' experiences with bonding.

I recall seeing a lot of dropped packets when doing drbd replication  
over bonded crossover cables in balance-rr mode.  Things were fine  
under normal circumstances, and drops showed up when I really loaded  
the primary.  active-backup gave me enough throughput, so I switched.   
That was on HP DL380s with Centos 5.5.  I don't recall which ethernet  
driver was in use.

alex


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