[DRBD-user] Meta device speed

[Lars Ellenberg]

/ 2005-08-21 23:50:17 +0930
\ David:
> Hi all,
> 
> I was just wondering - when using external meta data, stored on a separate
> physical device, how critical is the speed of that physical device to the
> overall performance of the drbd resource?

not too much. we have all sorts of tricks in place to reduce the number
of meta data updates. you could do
 watch -n1 cat /proc/drbd
and watch the bm: and al: numbers.
each increment there is a synchronous write to the meta data.
this happens during setup, during resync, and every now and then 
during normal operation. if it happens too often during normal
operation, you could increase the al-size parameter (with implications
for the resync time in case of a primary crash).

-- 
: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe   http://www.linbit.com :
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