[DRBD-user] DRBD over ZFS - or the other way around?

David Bruzos david.bruzos at jaxport.com
Wed Sep 6 16:22:23 CEST 2017

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


I've used DRBD devices on top of ZFS zvols for years now and have been very satisfied with the performance and possibilities that that configuration allows for.  I use DRBD 8.x on ZFS latest mainly on Xen hypervisors running a mix a Linux and Windows VMs with both SSD and mechanical drives.  I've also done similar things in the past with DRBD and LVM.  The DRBD on ZFS conbination is the most flexible and elegant.  You can use snapshotting and streams to do data migrations across the Internet with minimal down time while getting storage level redundancy and integrity from ZFS and realtime replication from DRBD.
A few scripts can automate the creation/removal of devices and coordinate VM migrations and things will just work.  Also, you can then use ZFS streams for offsite backups (if you need that kind of thing).
Another thing is that you may not need the realtime replication for some workloads, so in those cases you can just run directly on ZFS and omit the DRBD device.  At least for me, that great flexibility is what makes running my own configuration worth it.

Just my 25 cents!

David

-- 
David Bruzos (Systems Administrator)
Jacksonville Port Authority
2831 Talleyrand Ave.
Jacksonville, FL  32206
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Email: david.bruzos at jaxport.com

On Wed, Sep 06, 2017 at 03:03:32PM +0100, Yannis Milios wrote:
> ...I mean by cloning it first, since snapshot does not appear as blockdev
> to the system but the clone does.
> 
> On Wed, Sep 6, 2017 at 2:58 PM, Yannis Milios <yannis.milios at gmail.com>
> wrote:
> 
> > Even in that case I would prefer to assemble a new DRBD device ontop of
> > the ZVOL snapshot and then mount the DRBD device instead :)
> >
> > On Wed, Sep 6, 2017 at 2:56 PM, Gionatan Danti <g.danti at assyoma.it> wrote:
> >
> >> On 06/09/2017 15:31, Yannis Milios wrote:
> >>
> >>> If your topology is like the following:  HDD -> ZFS (ZVOL) -> DRBD ->
> >>> XFS then I believe it should make sense to always mount at the DRBD level
> >>> and not at the ZVOL level which happens to be the underlying blockdev for
> >>> DRBD.
> >>>
> >> Sure! Directly mounting the DRBD-backing ZVOL would, at the bare minumum,
> >> ruin the replication with the peer.
> >>
> >> I was speaking about mounting ZVOLs *snapshots* to access previous data
> >> version.
> >>
> >> Regards.
> >>
> >>
> >> --
> >> Danti Gionatan
> >> Supporto Tecnico
> >> Assyoma S.r.l. - www.assyoma.it
> >> email: g.danti at assyoma.it - info at assyoma.it
> >> GPG public key ID: FF5F32A8
> >>
> >
> >

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