Difficult to reply like that, it depends a lot on your architecture... Are you talking of external disks ? LUNS perhaps? how do you acces them (vai HBA's , how many?...)

striping can boost of course but then you are stuck with your policy... e.g. striping using 6 LUNs via 2 HBA will give great perfs, but the day you are short of space you are doomed if you cannot give 6 extra LUNS...
What follows can be achieved by letting the system use all you give:

Code:

n12:/home/vbe $ lslv -l lv111
lv111:/opt/oracle
PV                COPIES        IN BAND       DISTRIBUTION  
hdisk2            003:000:000   0%            000:000:000:003:000 
hdisk8            003:000:000   0%            000:000:000:003:000 
hdisk9            003:000:000   0%            000:000:000:003:000 
hdisk1            003:000:000   0%            000:000:000:003:000 
hdisk5            002:000:000   0%            000:000:000:000:002 
hdisk6            002:000:000   0%            000:000:000:000:002 

LOGICAL VOLUME:     lv111                  VOLUME GROUP:   vg01
LV IDENTIFIER:      00c8e5f200004c0000000123c1b0003f.13 PERMISSION:     read/write
VG STATE:           active/complete        LV STATE:       opened/syncd
TYPE:               jfs2                   WRITE VERIFY:   off
MAX LPs:            516                    PP SIZE:        128 megabyte(s)
COPIES:             1                      SCHED POLICY:   parallel
LPs:                16                     PPs:            16
STALE PPs:          0                      BB POLICY:      relocatable
INTER-POLICY:       maximum                RELOCATABLE:    yes
INTRA-POLICY:       middle                 UPPER BOUND:    6
MOUNT POINT:        /opt/oracle            LABEL:          /opt/oracle
DEVICE UID:         0                      DEVICE GID:     0
DEVICE PERMISSIONS: 432
MIRROR WRITE CONSISTENCY: on/ACTIVE
EACH LP COPY ON A SEPARATE PV ?: yes (superstrict)
Serialize IO ?:     NO
INFINITE RETRY:     no
DEVICESUBTYPE:      DS_LVZ
COPY 1 MIRROR POOL: None
COPY 2 MIRROR POOL: None
COPY 3 MIRROR POOL: None

But this is not what is commonly called stripes and so the day you are short in the VG you can add what you have and let AIX deal with it...

That said, tuning a system is knowing what is the best compromise for the appointed tasks to need to realize :
Stripping is very good but it has a cost... I remember seeing an HP-UX system striped over 180 disks using 16 HBAs...
But as I said tuning is finding an acceptable compromise, e.g. bigger the cache, less memory you have for your programs ...
Then of course e.g. oracle greater the SGA better the perfs. should be, only I noticed that this is not quite true, it will follow more something like a Gauss curve and so the best can be the ennemy of the Good.... (e.g. You can end with a system loooooosing such a time parsing the SGA for some data when reading from disk would already give the data...) Also having to many Caches will end with same sort of result ( If you are using a disk bay, it caches also so why let AIX use a lot of cache for your file systems... )
About disks/ LUNs the spindles you can give and spread over the more HBAs - bigger the throughput you have, but keep in mind you may be moving the problem forward: for it to be the most performant the ideal would be to have a LUNs from separate arrays using different controllers in the bay...
All this to say take your time defining correctly what your needs are because once your system is up, you will have to live with it