problems when reading large files under backup

[holdahl]

Does anyone know if there are any known problems with AIX v 5.2 when reading large files doing a backup?

Seems like one of our systems are using a lot of resources (like very high CPU utilization) when reading large files doing a backup from disk to tape.


-holdahl

 

[khalidaaa]

Are you using aio?

 

[khalidaaa]

lsdev -Cl aio0

 

[holdahl]

It says:

user1@server1:/home/user1> lsdev -Cl aio0
aio0 Available Asynchronous I/O (Legacy)

does this mean that aio is available but not used?
should it be used?


-holdahl

 

[Ogzilal]

Hi,
To see if you have aio servers running, you will see the number of servers declared :

# ps -u root|grep aioserver
    0  3756      -  0:00 aioserver
    0  4158      -  0:00 aioserver
    0  4714      -  0:00 aioserver
    0  5462      -  0:00 aioserver
    0  5680      -  0:00 aioserver
    0  5946      -  0:00 aioserver
    0  6216      -  0:00 aioserver
    ....

In my box, I have 40 aio servers running

Ali

 

[holdahl]

yes, have aioservers running on our boxes..



-holdahl

 

[khalidaaa]

Try increasing your aio servers. It could be that you don't have the required aio servers for your system!

Have a look into that nice article about AIO:

http://publib.boulder.ibm.com/infoc...ix.kernelext/doc/kernextc/async_io_subsys.htm

It would help as well if you can provide the output of vmstat and iostat during the backup!

Regards,
Khalid