[DRBD-user] The need for Speed 2

Philipp Reisner philipp.reisner at linbit.com
Fri Jan 14 11:53:41 CET 2005

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


Am Donnerstag, 13. Januar 2005 12:14 schrieb Lars Marowsky-Bree:
> On 2005-01-13T11:50:30, Philipp Reisner <philipp.reisner at linbit.com> wrote:
>
> Hi Philipp, interesting numbers, thanks!
>
> > A hint where we loose are the numbers from writing on DRBD
> > in disconnected mode:
>
> How much overhead goes into keeping the active log etc uptodate? Is the
> performance disk IO-, network IO- or CPU-limitted?
>

Ahhh, right. I had the AL at its default setting, so there were updates
to the AL, because I wrote 3G in my tests...

Now I changed the AL setting:

  syncer {
    rate 14M;
    group 2;
    al-extents 1009;
  }

Now the "al:" value stays constant during a test....

43.25 MB/sec (3221225472 B / 01:11.033546)
44.91 MB/sec (3221225472 B / 01:08.403583)
44.79 MB/sec (3221225472 B / 01:08.585322)

Raw write performance to the LVs:
59.69 MB/sec (3221225472 B / 00:51.468961)
60.54 MB/sec (3221225472 B / 00:50.743192)
60.71 MB/sec (3221225472 B / 00:50.603030)

So, when the working set stays constant, we now we reach 75% of the raw 
LVs performance ... with these machines.

-Philipp
-- 
: Dipl-Ing Philipp Reisner                      Tel +43-1-8178292-50 :
: LINBIT Information Technologies GmbH          Fax +43-1-8178292-82 :
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