[DRBD-user] Protocol A vs Protocol C performance issue?

Lars Ellenberg lars.ellenberg at linbit.com
Tue Oct 20 20:58:08 CEST 2015

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

On Tue, Oct 20, 2015 at 08:52:27PM +0200, Joeri Casteels wrote:
> > Throughput is concurrency times request size by request completion latency.
> > 
> > dd has no concurrency, in the given example, request size is 1M,
> > if you get 450 MB/s, your latency apparently is in the order of 2.3 ms.
> > 
> > If you want more throughput,
> > you need to decrease latency, or increase concurrency.
> Any suggestions on how to improve that then?

Increase concurrency?
Use something that has concurrency (as I said, dd has not; fio would have)
Or use more than one dd, concurrently ;-)

Decrease latency?
Check if it's your disk or network or both, and if possible,
make it complete stuff faster
(without losing it in volatile caches in the event of a hard crash).

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

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