[Lustre-discuss] Lustre and iSCSI

[Klaus Steden]

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
>> 
>> 
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