[DRBD-user] DRBD strange synchronization behaviour

Lars Ellenberg lars.ellenberg at linbit.com
Thu Jun 6 14:48:11 CEST 2013

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


On Mon, Jun 03, 2013 at 02:22:54PM +0200, Grzegorz Wolny wrote:
> Hi all,
> 
> I read article about DRBD 8.4.3 and performance improvement in
> random tests:
> http://blogs.linbit.com/p/469/843-random-writes-faster/
> 
> I compared DRBD 8.3.10 and 8.4.3 and achieved strange results.
> 
> * 300GB volume synchronization time:
> DRBD 8.3.10 - 00:18:24
> DRBD 8.4.3 - 00:52:06
> 
> * Sequence 300GB write time (DD)
> DRBD 8.3.10 - 00:42:12
> DRBD 8.4.3 - 00:37:37
> 
> * Random write test time (FIO)
> DRBD 8.3.10 - 03:19:07
> DRBD 8.4.3 - more than 1 day (after 3 hours interrupted)
> 
> Last test confirms that DRBD 8.4.3 is better than 8.3.10 in random
> test, but synchronization time is disturbing.
> Why synchronization time is more than 2 times faster on DRBD 8.3.10?
> What can I improve in my configuration?

So you benchmark heavy IO during concurrent full resync.
Not a particularly real-world benchmark, but whatever.

Maybe this helps:
http://lists.linbit.com/pipermail/drbd-user/2012-August/018900.html

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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