Re: [CentOS-virt] IBM GPFS filesystem

2010-12-02 Thread Evan Fraser
Adam Wead amsterda...@... writes:

 
 Hi all,I was wondering if anyone might be able to speak about using IBM's GPFS
filesystem as a means of storing virtual guests in a clustered environment with
CentOS as the nodes and KVM as the hypervisor?
 I'm looking at using IBM's TSM software for archiving data from disk to tape. 
This requires buying a license for GPFS which is used in conjunction with TSM
but can also be used as a clustered filesystem as well.  As I understand it,
GPFS can work with CentOS so long as you're using the right kernel.Is anyone out
there using CentOS+GPFS for their virtualization environment?many thanks in
advance,...adam
 
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Hi Adam,
I use GPFS as my filesystem for my Centos-Xenvirtual environment.

The Virtual servers are converted Compute nodes, running Centos 5.4 with Xen
3.4.2 and have Infiniband connectivity to the NSD servers.  The VM's all live on
the GPFS filesystem.  This has worked pretty well, the disk performance of the
VM's has been good when using the GPL paravirt drivers (my VM's are windows
server 2003).

I'm currently in the process of trying to re-setup the infrastructure using
stateless Centos+KVM Virtual servers instead, but its too early to tell if its
working or not.

Good luck,

Evan.



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Re: [CentOS-virt] IBM GPFS filesystem

2010-12-02 Thread carlopmart
On 12/02/2010 10:53 PM, Benjamin Franz wrote:
 On 12/02/2010 12:58 PM, compdoc wrote:
 []...live migration...?
 ___

 Interesting. Does live migration not work on ext3 or ext4?

 No. You need a shared filesystem.

Thats not true. You can do live kvm guest migration using RHEL/CentOS+RHCS+KVM 
using 
lvm volumes to allocate/install kvm guests, for example. In this case you don't 
need 
a shared filesystem ...

To accomplish a live kvm migration (or xen) you need a shared storage, not a 
clustered filesystem or shared filesystem.


  Which pretty much leaves you on either
 NFS or a clustered filesystem. RH has an example of using NFS - with a
 strong statement attached that you shouldn't do it that way in real life
 because the performance is poor.

I have two solaris zfs/nfs fileservers sharing storage to 5 ESXi servers and 
performance is very very good ... And it is a production system ...


 Trying to mount ext3 or ext4 simultaneously from two machines (on say
 iSCSI) would just result in filesystem corruption.

This case isn't possible, because you can't mount an ext3 or ext4 filesystem at 
the 
same time in two or more hosts ...




-- 
CL Martinez
carlopmart {at} gmail {d0t} com
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Re: [CentOS-virt] IBM GPFS filesystem

2010-12-02 Thread Fabian Arrotin
Benjamin Franz wrote:
 On 12/02/2010 12:58 PM, compdoc wrote:
 []...live migration...?
snip
 
 No. You need a shared filesystem. Which pretty much leaves you on either 
 NFS or a clustered filesystem. 

Totally wrong ! If you have never tested it , try it (and try to 
understand clvmd) before saying that it doesn't work !
If you've never tried it, that means you've never played with the rhcs 
stack, because even if you want to put gfs/gfs2 on top, you still need 
clvmd to have a consistent logical volume management across all the 
nodes in the hypervisor cluster ...
It seems to me that most people wanting to have a clusterfs 
(gfs/gfs2/ocfs2/whateverfs) on top of a shared storage want that just 
because they are used to that  thing that Vmware did for a shared 
storage : vmfs on top of a shared storage and file-based container 
(.vmdk) for the virtual machines.
I've installed several solutions based purely on lvm

Please compare all the solutions and you'll easily find that on a 
performance/IO level you'll be always faster to put put extra layer 
between the VM storage and the shared storage

-- 
--
Fabian Arrotin



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Re: [CentOS-virt] IBM GPFS filesystem

2010-12-02 Thread Rajagopal Swaminathan
Greetings,

On Fri, Dec 3, 2010 at 12:37 AM, Fabian Arrotin
fabian.arro...@arrfab.net wrote:
 Adam Wead wrote:
 Hi all,


 Why would so much people use a clusterfs for Virtualization ?
 Just use lvm and a logical volumes for your guests.

Did you mean CLVM? Where does snapshot stand?

bitty outta touch with tech these days...

Regards,

Rajagopal
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Re: [CentOS-virt] IBM GPFS filesystem

2010-12-02 Thread Pasi Kärkkäinen
On Fri, Dec 03, 2010 at 12:45:22PM +0530, Rajagopal Swaminathan wrote:
 Greetings,
 
 On Fri, Dec 3, 2010 at 12:37 AM, Fabian Arrotin
 fabian.arro...@arrfab.net wrote:
  Adam Wead wrote:
  Hi all,
 
 
  Why would so much people use a clusterfs for Virtualization ?
  Just use lvm and a logical volumes for your guests.
 
 Did you mean CLVM? Where does snapshot stand?
 
 bitty outta touch with tech these days...
 

You can also use normal LVM over shared iSCSI LUN,
but you need to be (very) careful with running LVM management commands
and getting all the nodes (dom0s) to be in sync :)

(Citrix XenServer does this, but there the management toolstack
takes care of the LVM command execution + state synchronization).

-- Pasi

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