Re: [Xen-users] Shared Storage

[Jonathan Tripathy <jonnyt@xxxxxxxxxxx>]

On 25/04/2011 18:34, John Madden wrote:
> > I would honestly prefer to manage hundred of LVs instead of hundreds of
> > LUNs. I'm just concerned about the iSCSI bottleneck (if any) if I were
> > to create an LVM VG using a single iSCSI LUN for about 50 - 100 LVs. Any
> > advice is appreciated.
> I'd be more concerned over iSCSI itself being able to scale based on 
> your workload, especially if you're doing it over GbE.  Even 50 VMs 
> doing relatively little though concurrently could cause problems given 
> the nature of iSCSI (TCP overhead, latency of ethernet, etc).
When you say this, are you refering to the suitation where I would have 
1 LUN per VM (i.e. 50 LUNs)? I would be doing this over GbE, however I 
would be using trunking
> My feel for this is that the fewer-LUN-more-LV route would be more 
> efficient because you'll have fewer block device queues and multipath 
> call-outs and such but that's just a guess on my part. 
Interesting. I have had a comment on this list suggesting the opposite.
> Test it out, see which one is better.  If there's  no difference, go 
> with the one that's easier to manage.
Hands down mamanging LVM is my number one choice. Ideally I would just 
like to set up the iSCSI connections once and just leave it

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