[Lustre-discuss] Lustre requirements and tuning tricks

[Joan J. Piles]

Hello all!

We are planning an upgrade to our current storage infrastructure, and we 
intend to deploy lustre to serve some 150 clients.

We intend to use 5 OSS with the following configuration:

- 2 x Intel 5520 (quad core) processor (or equivalent).
- 24Gb RAM.
- 20 x 2Tb SAS2 (7,200 rpm) disks.
- 1 x 16 and 1x8 ports Adaptec RAID controllers, with 20 SAS and 4 SSD 
drives.
- 2 x10Gb Ethernet ports.

And then 2 MDS like these:

- 2 x Intel 5520 (quad core) processor (or equivalent).
- 36Gb RAM.
- 2 x 64Gb SSD disks.
- 2 x10Gb Ethernet ports.

After having read the documentation, it seems to be a sensible 
configuration, specially regarding the OSS. However we are not so sure 
about the MDS. We have seen recommendations to reserve 5% of the total 
file system space in the MDS. Is this true and then we should go for 
2x2Tb SAS disks for the MDS? Is SSD really worth there?

And we have also read about having a separate storage for the OSTs' 
journals. Is it really useful to get a pair of extra small (16Gb) SSD 
disks for each OST to keep the journals and bitmaps?

Finally, we have also read that it's important to have different OSTs in 
different physical drives to avoid bottlenecks. Is thas so if we make a 
big RAID volume and then several logical volumes (done with the hardware 
raid card, the operating system would just see different block devices)?

Thank you very much in advance,

Joan

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Joan Josep Piles Contreras -  Analista de sistemas
I3A - Instituto de Investigación en Ingeniería de Aragón
Tel: 976 76 10 00 (ext. 5454)
http://i3a.unizar.es -- jpiles at unizar.es
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