[Lustre-discuss] multiple OSTs accessing the same shared storage simultaneously?

Marcus Schull c.schull at imb.uq.edu.au
Mon Jul 28 23:58:18 PDT 2008


Hi,

I am fairly new to lustre and clustered filesystems having only  
configured SAM-QFS shared filesystems before.  At my work, we are  
planning to deploy a lustre filesystem on RHEL5 systems running on  
top of VMware ESX 3.x.
We are hoping to serve 2 filesystems of 3 and 4 TB respectively via  
10 OSS VMs (1 per ESX host) and 2 MDS VMs (in failover configuration)  
to service about 40 lustre clients (also VMs) running parasol or  
similar.

Due to ESX limitations, each LUN had to be <=2TB, (the disk is  
exported from a SAN) and so in our case each OSS can  see 7 1T LUNS/ 
disks, of which 3 are formatted (mkfs.lustre) and associated with  
"filesystemA" and the other 4 associated with "filesystemB".
We were hoping that each OSS could "share" both complete filesystems  
(ie all 7 TB) to client VMs running locally (for the increased  
performance of the networking within the same VMware host), but that  
these client VMs could also access the same data from any other OSS  
in the VMware cluster if required.

I have looked through the manual, on google and some of the discusion  
list archives to confirm whether this could be done, and it appears  
it can't.  Am I correct in the following observation:

* Even though you can have multiple OSS's and OSTs with failover, at  
any one time only one OSS can be accessing a particular block device/ 
LUN.  They can failover the shared storage between them, but can't  
simultaneously serve data from the same LUN and partition.   ??

I am sorry if I am asking a question that has already been asked on  
numerous occasions.

Thanks,

Marcus.

Systems Administrator.
University of Queensland.



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