We are reviewing database container design where the storage layer is
an EMC DMX 3 Raid 5 San.

The SAN comprises multiple raid 5 arrays, four disks in each array.
We have been allocated 8 gig virtual hypervolumes(LUNS) each mapped
horizontally across the four disks.  The 8 gig hyper volumes are split
into 2 gig hypers one hyper per disk.  The SAN stripe size is 768KB.

Hypervolumes are exposed to AIX as hdisks hence each hdisk is 8 gig.
The data on each hdisk is mapped across four physical drives in
contiguous stripes (tracks) of 2 gig(hypers).

For this example let's say we create four DMS containers(files) of 8
gig each for a tablespace.

Assign one hyper volume(hdisk) to each container.

Assign the four hdisks to logical volume 01.

The containers are c1, c2, c3, c4.
The hypers are c1/d1, c1/d2.......c4/d3, c4/d4.

       D1  D2  D3  D4
      .---. .---. .---. .---.
C1   | 1 | | 1 | | 1 | | 1 |    <=== hypervolume hdisk1 8 gig
C2   | 2 | | 2 | | 2 | | 2 |    <=== hypervolume hdisk2 8 gig
C3   | 3 | | 3 | | 3 | | 3 |    <=== hypervolume hdisk3 8 gig
C4   | 4 | | 4 | | 4 | | 4 |    <=== hypervolume hdisk4 8 gig
      ` ---' `---' `---' `---'

DB2 writes data in extents over the containers in a round robin
fashion. If the
tablespace extent size is set to 768KB then the data is written out in
768KB chunks in the
order c1/d1, c2/d1, c3/d1, c4/d1, c1/d1, c2/d1, c3/d1, c4/d1.

The SAN writes data in stripe order,  left to right . c1/d1, c1/d2, c1/
d3, c1/d4, c2/d1.....

We assume that all the disks in the array are dedicated to our host

My questions are:

1.  Will the SAN write to disk in the same sequence as DB2?  E.G if
DB2 is writing to C3/D1 could the SAN actually allocate the data on C2/
D4 because C2/D4 has no data or will it respect the hypervolume and
write on D3.

If the SAN follows the same allocation logic as DB2 then.......

2.  Will all the activity be on disk one until the first two gigabytes
in one of the containers is filled and DB2 moves to the next disk e.g
disk2 becomes active when the c1/d1 hyper is full and db2 moves to c1/
d2?

3.  If the data in each of the containers never exceeds 2 gig will
disk 1 be the only active disk in the array?