AIX

Hi,

I have a bit of a NFS problem on AiX 6.1 : When I set the mount to cio and dio - needed for a database app - Everything slows down. The following is copying 700mb, top one is a normal mount bottom one is a mount with the cio/dio option enabled :

# ./a.sh
Wed Jan 11 11:41:24 GMT 2012
Wed Jan 11 11:41:36 GMT 2012

# ./a.sh
Wed Jan 11 11:42:09 GMT 2012
Wed Jan 11 11:44:00 GMT 2012

Has anyone any ideas of how I could sort this?

Regards

Adam

With A61 it should not be necessary any more to explicitly use the cio mount option.

If your db is DB2 or Oracle this should rather be activated at the db profile level, e. g. using < filesystemio_options = SETALL > for Oracle.

Simply spoken, cio and dio options are effectively bypassing filesystem caching and read-ahead logic causing severe performance hits for any 'normal' application.

Hope this helps.
Regards
Greg

Hi,
dio is for JFS filesystems only - I doubt you are using jfs anywhere of your box - if you do that is part of your problem

for the cio part, - I am with Z80A - if you are using oracle, than you should use SETALL as oracle setting since Oracle 9.

If you are copying files into a cio mounted device, than thre is no filesystem buffering, as cio is switching it off. So if you copy anything, than you are saturating your disks. You are much better off, if you are mounting your filesystems without cio but with noatime options

Regards
zxmaus

Hi,

Thanks for the info I have removed the dio option. I really wish this was Oracle but its not - Open Text (formally known as BASIS) db's.

I do not know your DB at all but you should use cio in any case only for the real database files (.dbf on oracle) and not for binaries, dumps and similar filesystems - and I would not think you are really sharing the Database files themselves via nfs ?

zxmaus - Again I wish this was oracle and I wish it was my choice but sadly not - Yes the db files are on a netapp - connected to a power 7 box running aix 6.1