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Re: [Xen-users] remus vs. pacemaker/drbd?

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] remus vs. pacemaker/drbd?
From: Łukasz Oleś <lukaszoles@xxxxxxxxx>
Date: Wed, 8 Sep 2010 12:22:30 +0200
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On Tuesday 07 September 2010 18:46:58 Miles Fidelman wrote:
> Greg Woods wrote:
> > On Tue, 2010-09-07 at 09:28 -0600, Nick Couchman wrote:
> >> Pacemaker/DRBD, on the other hand, just synchronizes the data,
> >> and if it detects that one of the domUs has died, starts it up somewhere
> >> else.
> >> 
> >>   So, with Remus, the theory/goal is 0 downtime of your domU, whereas
> >>   Pacemaker
> >> 
> >> simply minimizes downtime to a certain point - the time it takes to
> >> detect failure
> >> 
> >>   and boot the new domU.
> > 
> > Actually, pacemaker can do live migrations with some limitations. If the
> > 
> > I have no experience with Remus, but from Nick's description of it, it
> > sounds like Remus might be a whole lot easier to set up and may be a
> > good way to go if all you care about is failover for your domU's, or if
> > you really need instantaneous failover in the event of a server crash.
> All of this is well and good, but not to the point.
> I'm using pacemaker and DRBD.  It works.  it's just a pain.
> Has anybody on this list actually used Remus in production?  Is it ready
> for prime time?  Or is it still beta (or alpha)?

Remus have very simply heartbeat(1s timeout), so in networks with heavy load 
it can failover without reason. 
To work properly it needs integrate with for example peacemaker(it's not 
implemented), so pain will stay.

Another problem is that Remus with disk replication doesn't support failback.

So in my opinion it's not production ready.


Łukasz Oleś

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