Our disks are RAID-5 and few are 2-way-mir.

I will try to migrate the disks the DBA's are complaining about to 2-way-mir.

We are going to decomm this array in 2012 so adding DA's might not jive with the upper management.

If we were to add DA's we will have to purchase disks and then migrate to the newly created disks on these DA's correct?

Every single DA director in the entire array is at 90% utilized. Will have to move these over to a new array.

Is that our only option?

move workload to less busy drives (host based mirroring,  symm oprimizer ? )

Yes, if you added DAs and disks, you would need to migrate some applications to the new DAs.   

Can we just buy DA's and not disks and still distribute the load?

This is most likely a dumb question but please bear with me here.

Yes there are a couple of oracle DBA's complaning about performance issues.

Only 1 host though. I am thinking we will just migrate that one host over to our VMAX and wait untill someone else complains.

Thanks everyone

Are any of the hosts experiencing a performance issue?  If not then running the backend at that rate, while high, may very well be acceptable.  fi you are tech refreshing it in less than a year you may be able to wait it out so to speak.  If its attached to a mainframe that hgih of a workload is not unusual; mainframe attached arrays always seem to have  avery high % utilized on the DA's.  If you get additional DA's yes you need to put disk drives behind them.