[Lustre-discuss] mkfs.lustre and disk partitions

[Kilian CAVALOTTI]

Hi Jim,

On Monday 04 February 2008 07:04:10 am Jim Albin wrote:
> Hello,
>  I've seen several notes mentioning the disadvantages of using disk
> partitions on the storage devices for Lustre OSTs (and/or MDTs). My
> questions, if anyone can help me, are;
>
> 1) Should I delete any existing partitions on the device?

There's no need to explicitely destroy the partitions if you overwrite 
them.

> 2) If not, should I partition the device into a single partition with
> a specific block size (maybe 1mb)?

No need either. One single partition is still a partition.

> 3) Can I just use the disk block device (eg, /dev/sda) when I
> mkfs.lustre and is it
> smart enough to ignore the partition table?

Yes, exactly. Generally speaking, mkfs /dev/sdb will use the whole sdb 
device for the filesystem, and you won't have any partition table. As a 
consequence, you won't be able to boot from it, which is not relevant 
here, but all the other operations will work as on any regular 
partition (tunefs, mount, etc).

> I'm trying to set up Lustre 1.6.3 and am seeing poor performance,
> possibly fragmentation on the mdt and ost.
> Thanks in advance for any suggestions.

I don't know what backend hardware you're using, but in case of Dell 
MD1000s, you probably can give a look (and a try) at: 
http://thias.marmotte.net/archives/2008/01/05/Dell-PERC5E-and-MD1000-performance-tweaks.html

HTH,
Cheers,
-- 
Kilian