[Lustre-discuss] Lustre and iSCSI

[Andreas Dilger]

On Aug 04, 2009  09:58 -0300, David Pratt wrote:
> Hi. Many thanks for your responses. Generally, the qualities of Lustre  
> appear great for a Storage Repository for virtual machine images in  
> XenServer since you would get a combination of fault tolerance, a  
> pretty much infinitely scalable distributed storage pool, speed and  
> ability to migrate virtual machines across a number or hosts.  
> XenServer can use NFS, iSCSI, NetApp, EqualLogic or Fibre Channel  
> storage repositories at this point. It appears there is some  
> capability to create a plugin to allow for others. It is possible that  
> the only way to get Lustre to work would be with the development of a  
> plugin.

You can re-export Lustre via NFS to these clients.

> At this point, to create a minimal Lustre install to play  
> with, how many machines will be required?

Depends on how available/robust you need the system.  A "functional"
system can run on a single node (MDS+OSS+client+NFS server).  A
highly available system needs at least 3 nodes (MDS, OSS, client+NFSd),
with the MDS and OSS doing failover for each other.

That said, unless you plan to scale beyond this (i.e. multiple OSS
nodes) you could just use a pair of nodes for an HA NFS configuration,
which is arguably less complex.

> On 3-Aug-09, at 8:01 PM, Klaus Steden wrote:
> > Hi David,
> >
> > I did some experiments last year with Lustre 1.6.x and a Dell iSCSI
> > enclosure. It was a little slow (proof of concept mainly) due to  
> > sharing MDT
> > and OST traffic on a single GigE strand, but as long as the  
> > operating system
> > presents a valid block device, Lustre works fine.
> >
> > hth
> > Klaus
> >
> > On 7/31/09 11:13 AM, "Cliff White" <Cliff.White at Sun.COM> etched on  
> > stone
> > tablets:
> >
> >> David Pratt wrote:
> >>> Hi. I am exploring possibilities for pooled storage for virtual
> >>> machines. Lustre looks quite interesting for both tolerance and  
> >>> speed. I
> >>> have a couple of basic questions:
> >>>
> >>> 1) Can Lustre present an iSCSI target
> >>
> >> Lustre doesn't present target, we use targets, and we should work  
> >> fine
> >> with iSCSI. We don't have a lot of iSCSI users, due to performance
> >> concerns.
> >>
> >>> 2) I am looking at physical machines with 4 1TB 24x7 drives in  
> >>> each. How
> >>> many machines will I need to cluster to create a solution with  
> >>> provide a
> >>> good level of speed and fault tolerance.
> >>>
> >> 'It depends' - what is a 'good level of speed' for your app?
> >>
> >> Lustre IO scales as you add servers. Basically, if the IO is big  
> >> enough,
> >> the client 'sees' the bandwidth of multiple servers.  So, if you know
> >> the  bandwidth of 1 server (sgp_dd or other raw IO tools helps) then
> >> your total bandwidth is going to be that figure, times the number of
> >> servers. This assumes whatever network you have is capable of sinking
> >> this bandwidth.
> >>
> >> So, if you know the IO you need, and you know the IO one server can
> >> drive, you just divide the one by the other.
> >>
> >> Fault tolerance at the disk level == RAID.
> >> Fault tolerance at the server level is done with shared storage
> >> failover, using linux-ha or other packages.
> >> hope this helps,
> >> cliffw
> >>
> >>> Many thanks.
> >>>
> >>> Regards,
> >>> David
> >>>
> >>>
> >>> ------------------------------------------------------------------------
> >>>
> >>> _______________________________________________
> >>> Lustre-discuss mailing list
> >>> Lustre-discuss at lists.lustre.org
> >>> http://lists.lustre.org/mailman/listinfo/lustre-discuss
> >>
> >> _______________________________________________
> >> Lustre-discuss mailing list
> >> Lustre-discuss at lists.lustre.org
> >> http://lists.lustre.org/mailman/listinfo/lustre-discuss
> >
> 
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.