[DRBD-user] DRBD deadly slow

[Felix Zachlod]

Hello!

Lars Ellenberg schrieb:
> 
> as your controller cache has a working BBU,
> you can safely use "no-disk-flushes;"
> starting with drbd 8.2.7,
> you should then also say "no-disk-barriers;".
> 
> verify that the settings are actually used with
>  drbdsetup /dev/drbd0 show

Thanks to all for their answers. Verifiing the configuration using the 
drbdsetup tool led me to recognize that the options set in the drbd.conf 
file are not being inherited to the single drbd devices once set in the 
global context- and so setting the paramters for each drbd- device led 
to a dramatical increase in sync rate from about 3MByte/s to about 
50MByte/s- BUT- this is still far below the io-performance of the 
io-subsystem.

I read that the performance should be something like 10-15% lower than 
the io-subsystems's performance respectively the network-performance.

I tried to raise the syncer: rate parameter but this does not change 
anything. My syncer rate seems to be very constant about 50MByte/s- as I 
read the syncer rate is not of interest for live write performance but 
only for the resynchronisation process.

Are there any further paramters that might cap my write performance to 
that 50MByte/s?

Thank you in advanced,
best regards,
Felix