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

Joeri Casteels joeri.casteels at intec.ugent.be
Tue Oct 20 18:27:50 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 20 Oct 2015, at 18:23, Digimer <lists at alteeve.ca> wrote:
> On 20/10/15 11:47 AM, Lionel Sausin wrote:
>> Le 20/10/2015 17:30, Joeri Casteels a écrit :
>>>> Protocol A an async, C is sync. So you're probably hitting the network
>>>> limit on C.
>>> I don’t think so since it has a direct 20G trunk in-between with perf
>>> i get 19.6Gbit/s on single threat. With A (async when i monitor the
>>> network it also hits 2x the network speed as C does)
>> "sync" means the round-trip time (down to the remote disks) is what
>> counts, not the bandwidth.
> Correct.
> In protocol C, the write is not completed until it has hit persistent
> storage on both nodes. I guessed it was your network, but it could also
> be your disk.
> Also, use 'fio', not 'dd' to test performance.

Can you give me the correct fio cmd then i’ll run that with protocol A and C and post the difference… 

> -- 
> Digimer
> Papers and Projects: https://alteeve.ca/w/
> What if the cure for cancer is trapped in the mind of a person without
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