[DRBD-user] tuning DRBD

[Ben]

Thanks for the response, Lars. Followup questions below....

On Jun 12, 2007, at 9:19 AM, Lars Ellenberg wrote:

>> 2. Can I eck out more throughput by increasing sndbuf-size? Does that
>> increase my write latency when using Protocol C?
>
> most likely not.

Is that a no on the throughput, the increased latency, or both? :)

>> 3. What's a reasonable formula for determining max-buffers? Does
>> increasing them imply I should increase something else too?
>
> that number is basically in "pages", iirc, so if you compare
> (max-buffers * 4k * number of drbd's in use) to your physical RAM,
> it should be some not too impressive number.

Got it. Is there a benefit to increasing it?

>> 5. Does decreasing max-epoch-size reduce my write latency?
>
> most likely not.

What are the tradeoffs with turning this knob, then?

>> Does anybody have any experience playing with the schedulers in the
>> 2.6 kernel?
>
> yes of course.
> but the answers here depend very much on what you specifically ask  
> for.

I'm looking to make me a database cluster, so I'm looking to minimize  
latency for random reads and writes.