[DRBD-user] Hardware-recomendation needed

Felix Frank ff at mpexnet.de
Tue Apr 3 12:03:26 CEST 2012

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


On 04/03/2012 11:53 AM, Lukas Gradl wrote:
> For use with KVM with automatic failover I need a primary/primary setup,
> so AFAIK protocol C is required.

For dual-primary it is required, yes. You do need dual-primary for live
migrations. You do *not* need it for automatic failover (in failure
scenarios, live migration won't do you any good, anyway).

If live migration isn't an issue for you, single-primary is perfectly
fine! You still want protocol C though :-)

> According to my benchmarks DRBD is much slower in that setup than native
> HDD performance and changing the Network-Setup from 1GBit direct link to
> 2 bonded interfaces doesn't increase speed.

Have you identified the exact bottleneck inside your DRBD setup?
Have you done analysis according to

> What do the experts think: Should this be sufficient to get the
> perfomance of a single SATA-Disk without DRBD?

I don't really feel addressed ;-) but here's my 2 cents:

If DRBD performance with rotational disks is dissatisfactory, I wouldn't
count on faster disks somehow solving the problem. You *may* save enough
latency to make the setup worthwhile, but myself, I'd rather keep trying
to root out the main problem.
Throwing SSDs at a slow setup in order to make it a mediocre setup seems
awfully wasteful to me.


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