[DRBD-user] invalidate-remote does not work in StandAlone mode

Felix Frank ff at mpexnet.de
Fri Aug 5 11:55:47 CEST 2011

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


Hi,

On 08/05/2011 11:44 AM, Mark wrote:
> I'm inserting the DRBD layer for on-demand VM migration purposes. Data
> redundancy is by default done using local soft or hardware raid only, it
> is not a failover or a network raid scenario. DRBD is only used to
> minimize downtime while migrating the VM to another host which is not
> known beforehand.

Hmm. So you will accept a full sync before the migration takes place?
Seems wasteful, and I'm not sure you save all that much by running
StandAlone.

> I could possibly do that by using the dm layer to put the DRBD under the
> VM when needed, but the disabled AL would be simpler and probably less
> error-prone.
>> Have you compared Standalone DRBD performance with performance when not
>> > using DRBD at all?
> well, I tested disabled AL against active AL. It's 100 random buffered
> write ops against 40 per second. And yes, some work loads here are pretty
> much like that. :-/

You can disable the AL? News to me, but sounds good in your scenario.

If this works, why don't you go AL-less? Seeing as you don't want to use
a peer, there is nothing DRBD could do with its hot extents if it tried.

HTH,
Felix



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