Re: [HPDD-discuss] Lustre Pools vs Multiple Lustre File System recommendation
On Jul 21, 2014, at 10:15 AM, "Kumar, Amit" <ahkumar(a)mail.smu.edu> wrote:
Lustre v2.4.3:
SL 6.5 (client)
SL 6.4 (server)
Seeking for recommendations on setting up multiple Lustre file system “versus” creating
multiple pools with exclusive OST’s.
We have two sets of disks SAS vs SATA and would like to separate them. I have created
exclusive OST pools and they seem to work fine, but I am looking for recommendations
before we go into production with this setup.
We have 12 OSS and all of the SAS & SATA OST’s are evenly spread across 12 OSS’s.
If you want to ensure that files only exist on one type of storage, then using multiple
file systems would do that. As far as I know, even if you define pools for the different
types of drives, a user could still choose not to use either pool and spread the file
across SAS and SATA drives. For multiple file systems though, you will need to have a
separate MDT for each one.
Using OST pools has the benefit of offering some flexibility. With two different file
systems, you have a hard boundary. Files can only exist on one file system or the other.
With OST pools, you always have the option of allowing a file to be striped across all the
OSTs. Obviously the performance characteristics would not be uniform, but it might turn
out that an application doesn't need the full capabilities of a SAS OST and it's
more beneficial if the application uses as many OSTs as possible.
The best choice depends a lot on how the file system will be used (and I don't know
those details). But if you are currently using pools and it is meeting your needs, I
would be inclined to stick with that.
--
Rick Mohr
Senior HPC System Administrator
National Institute for Computational Sciences
http://www.nics.tennessee.edu