[DRBD-user] LVM under DRBD resource for NFS server

Lars Ellenberg lars.ellenberg at linbit.com
Thu Jun 25 22:46:28 CEST 2015

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

On Sat, Jun 20, 2015 at 08:57:36AM +0200, Marco Marino wrote:
> Hi,
> I'm trying to build an high available nfs server with drbd and pacemaker. I
> have some doubts related to the devices and the drbd resource. Following
> the guide "NFS on RHEL6" on the linbit site, I found that under the drbd
> resource there is a Logical Volume:
> PV -> VG -> LV -> DRBD resource ....
> Now i have a large storage server with a /dev/sda of 72TB. I would use 3TB
> for nfs, so with gparted I created /dev/sda1 of 3TB. My question is: should
> I use lvm?Reading this
> <http://askubuntu.com/questions/3596/what-is-lvm-and-what-is-it-used-for>,
> turns out that "if you use LVM across hard drives you may loose all your
> data when only one drive fails."

That translates to "If you use LVM to just concatenate component block devices"
or "stripe over component block devices without redundancy" (aka raid0),
and you lose one of the component devices, obviously that is lost.

Which is just common sense,
and is certainly not any shortcoming with LVM.

> and this is my case, so is this a good idea? Considering that i don't need
> to resize /dev/sda1, can I avoid the use of LVM?

You can, but that does not make a difference,
only limits you in flexibility.

You should probably use LVM *instead* of partitioning.

	Lars Ellenberg

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