Bad performance on AIX 6.1 TL5 TL7 environment

[tsmrolof]

we have a new TSM environment. Brand new p740's and each tsm server has its own dedicated VNX5300 storage box.
emc has proven on site that the storage can handle the load. They used a tool called IOrate.
for as long as the data was written to raw devices the performance was great, around 250 MB/s. But as soon as we started to write to the JFS2 filesystems the performance collapsed to around 20 MB/s.
I know raw devices always have a better performance then a jfs2 but the gap we see now is just to big.
Has anyone experienced the same?

Thanx,

Rolof

 

[chad_small]

I love using RAW volumes for storage pools. Just easier to create and use, but...according to IBM there should be a negligible difference. The problem is that the negligible difference depends on tuning so make sure your filesystems are created for best performance. You can read more about this at http://www.ibm.com/developerworks/aix/library/au-aixoptimization-disktun3/. (for some reason I am not seeing the formatting features so cut an paste the link).

 

[tsmrolof]

Hi Chad,
thanks for the info.
A aix minde collegue of mine suggested to use DIO.
This boosted the performance. we are now close to RAW lv performance!
The link you gave will help us to tune the performance even beter.

Grtz,

Rolof.