[DRBD-user] 4TB limit

Ralf Gross Ralf-Lists at ralfgross.de
Thu Oct 19 15:48:36 CEST 2006

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

Lars Ellenberg schrieb:
> / 2006-10-19 09:42:03 +0200
> \ Ralf Gross:
> > 
> > if I understand the documentation correct, there is a limit of ~4TB
> > for a single drbd device on 32bit systems. Furthermore lvm on top of a
> > drbd device is not recommended.
> > 
> > What is the recommended way to use drbd and lvm for filesystems that
> > are >4TB. My aim would be to have only one mount point, hence lvm on
> > top of drbd would be desired.
> the reason why it is not recommended is that you may run into funny
> things in the lvm part when only part of the drbd pvs are Primary
> on the node...  and several TB of storage takes ages to initialize
> with current drbd 0.7.

At the moment I'm testing the setup with two vmware instances and
partitions that are only a few hundered MB large.

We'll see how this works on the production system in a few weeks ;)
> but as long as your heartbeat scripts do behave, and you generally know
> what you are doing, it is certainly possible to have lvm on top of drbd
> without problems.

Ok, good to hear that from you.
> btw,
> drbd-plus can (currently) handle 16TB per device, and initializes
> much faster.  you have to by a licence from linbit,
> but you get an implicit support contract for it, too.

I've seen this. At the moment it's hard to get money for non Win OS
software here. So I'm stuck with the simple drbd solution - which I
think will be adequate for us.


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