- To: Slug <slug@xxxxxxxxxxx>
- Subject: Re: [SLUG] Network Real-Time Hot Filesystem Replication?
- From: "Amos Shapira" <amos.shapira@xxxxxxxxx>
- Date: Sun, 6 Apr 2008 21:17:11 +1000
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On Sun, Apr 6, 2008 at 9:25 PM, Adrian Chadd <adrian@xxxxxxxxxxxxxxx> wrote:
> On Sun, Apr 06, 2008, Amos Shapira wrote:
>
> > I've been using DRBD for a few months now (just in stand-by mode, but
> been
> > following the forums and docs during that time) and all indications are
> > that:
> >
> > 1. You CAN'T mount a non-cluster-aware file system even read-only on the
> > secondary node since the primary will change FS-structs under the feet
> of
> > the read-only node and cause it to crash (because non-cluster-aware
> > filesystems assume that they are the only ones who touch that
> partition).
>
> > 2. You CAN mount read-write on multiple nodes if you use one of the
> > cluster-aware filesystems (GFS and OCFS are regularly mentioned, but if
> you
> > find any other cluster-aware file system then it sounds like it will
> work
> > too).
>
> IIRC they assume a single back-end device. Does DRBD give you a journaling
> block device which will stall updates until they've been pushed? How will
> the FSes tolerate the device IO being possibly milliseconds later than the
> master?
Again - I haven't got around to actually use it (as much as I'd like to just
sit down and try it) but you can see in the link that I sent with my
previous reply that they clearly claim that it is supported.
> Have you tried this suggestions? From all I read about DRBD this will
> cause
> > all secondary nodes to crash.
>
> I looked into it about a year ago and I couldn't find any simple way of
Could it be that you looked at 0.7? I always used 0.8+ and got the
impression that there were major improvements introduced in it over 0.7.
doing this using free software. There's CODA/AFS as possible solutions but
> they still push the notion of master/slave rather than equal peers, which
> Chris mentions he needs (ie, constant synchronisation between each member
> rather than periodic pushback..)
That's what DRBD 0.8+GFS/OCFS is promoted as .
Cheers,
--Amos
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