[Lustre-discuss] MDT raid parameters, multiple MGSes

[Thomas Roth]

Hi all,

we have gotten new MDS hardware, and I've got two questions:

What are the recommendations for the RAID configuration and formatting 
options?
I was following the recent discussion about these aspects on an OST: 
chunk size, strip size, stride-size, stripe-width etc. in the light of 
the 1MB chunks of Lustre ... So what about the MDT? I will have a RAID 
10 that consists of 11 RAID-1 pairs striped over. giving me roughly 3TB 
of space. What would be the correct value for <insert your favorite 
term>, the amount of data written to one disk before proceeding to the 
next disk?

Secondly, it is not yet decided whether we wouldn't use this hardware to 
set up a second Lustre cluster. The manual recommends to have only one 
MGS per site, but doesn't elaborate: what would be the drawback of 
having two MGSes, two different network addresses the clients have to 
connect to to mount the Lustres?
I know that it didn't work in Lustre 1.6.3 ;-) and there are no apparent 
issues when connecting a Lustre client to a test cluster now (version 
1.8.4), but what about production?


Cheers,
Thomas