[DRBD-user] Slower disk throughput on DRBD partition

Lars Ellenberg lars.ellenberg at linbit.com
Thu Feb 2 15:15:11 CET 2012

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


On Wed, Feb 01, 2012 at 10:18:25PM +0100, Andreas Kurz wrote:
> On 02/01/2012 05:15 PM, Frederic DeMarcy wrote:
> > Hi Andrea
> > 
> > Commenting out "csum-alg" doesn't seem to make any noticeable difference...
> > However commenting out "data-integrity-alg" and running Test #2 again
> > increases the throughput from ~ 61MB/s to ~ 97MB/s !
> > Note that I may well run into the 1Gb/s crossover link limit here since
> > my network tests showed ~ 0.94 Gb/s
> > 
> > Also Test #1 was wrong in my email... It should have been split in 2:
> > Test #1
> > On non-DRBD device (/dev/sda)
> > # dd if=/dev/zero of=/home/userxxx/disk-test.xxx bs=1M count=4096
> > oflag=direct
> > Throughput ~ 420MB/s
> > 
> > DRBD partition (/dev/sdb) on primary (secondary node disabled)
> > Using Base DRBD config
> > # dd if=/dev/zero of=/var/lib/mysql/TMP/disk-test.xxx bs=1M count=4096
> > oflag=direct
> > Throughput ~ 205MB/s
> 
> Is the result the same if you execute a "drbdadm invalidate-remote
> mysql" on the primary before doing the "single node" test? .... that
> would disable activity log updates ...

... with recent enough versions of DRBD.
Only the OP seems to be using 8.3.7.
Maybe you should consider an upgrade?


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



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