[Linux-cluster] slow I/O on v7000 SAN

[Bob Peterson]

----- Original Message -----
| Hello -
| 
| We are experiencing extreme I/O slowness on a gfs2 volume on a SAN.
| 
| We have a:
| 
| Netezza TF24
| IBM V7000 SAN
| IBM Bladecenter with 3 HS22 blades
| Stand alone HP DL380 G7 server
| 
| 
| The 3 blades and the HP DL380 are clustered using RHEL 6.1 and
| clustersuite 5.5.
| 
| We have 2 clustered volumes on different storage pools (one has 10k
| drives the other 7.2k).
| 
| We have an internal test that reads a large file (950G) using fopen
| and
| memmap. On a standalone server in a datacenter (Ubuntu Raid 5 10k
| disks)
| the tests take approximately 75seconds to run.
| 
| On the blades the test takes 300 - 350 seconds.
| 
| I have been looking at the cluster conf; any gfs tuning I can find. I
| am
| not really sure what I should post here?
| 
| yrs
| 
| Michael
| 
| --
| 
| 
| Michael Bubb
| System Administrator
Hi Michael,

It sounds like you probably ran into our "Large File Allocate" bug.
This is solved in recent kernels, including 5.7.z, 5.8, 6.3, etc.
More info here:

https://bugzilla.redhat.com/show_bug.cgi?id=683155

Regards,

Bob Peterson
Red Hat File Systems