[DRBD-user] Multi-disk devices possible?

Felix Frank ff at mpexnet.de
Fri Jun 3 13:20:10 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.

On 06/03/2011 12:26 PM, Sebastian wrote:
> Do you think I would see much performance benefit
> from running my O/S (see next para for details) directly on the bare metal?

I have no idea. Disk I/O is generally the bottleneck in virtualization
setups, but DRBD overhead usually has much to do with network latency
and throughput, which in turn are supposed to virtualize quite well.

So, if you're facing performance issues, you may want to do some tests,
but I don't see an immediate need to loose the virtualization layer.

> /dev/sdb2 ~ 1 TB - /dev/drbd1 (actually LVM so /dev/mapper/vg0drbd-filer) -
> used for NAS
> /dev/sdc1 ~ 1 TB - /dev/mapper/tempnas-tempnasv LV

Is DRBD on top of LVM or vice versa?
If DRBD is on top, you should have an easy ride indeed.

> What would be the benefits and
> disadvantages of splitting 1 mounted LV filesystem over 2 DRBD devices?

You mean, create two DRBDs, make both LVM PVs and have an LV span both?

Don't. Just don't. Imagine an FS that depends on two resources that can
each indepentently be available on only one of your HA nodes. Don't put
yourself into this position.

> When you say "scrub", I presume that is
> optional?

It is.


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