My customer is migrating to z/VM 5.2 with the SPE that provides PAV. I'v
e
been reading the CP Planning & Admin manual and remain with 2 questio
ns and
a remark.
I read:
2. You should not use PAV alias volumes as z/VM installation volumes
(for example, do not use for the 520RES volume).
This can lead to confusion: at first I concluded that 520RES could not be
on
a PAV volume. Adding "use a PAV base address instead" would avoid this.
Or
as the previous restriction tells
1. A virtual alias subchannel cannot be IPLed.
one could combine 1. and 2. and avoid the confusion too:
A virtual alias subchannel cannot be IPLed. Consequently you
should not use PAV alias volumes as z/VM installation volumes
(for example, do not use for the 520RES volume).
(as currently "1." and "2." are separate restrictions, one doesn't think
that "1." causes "2." and one starts wondering what the reason for "2." i
s)
I also read:
3. z/VM Paging and SPOOLing operations do not take advantage of PAV.
It is recommended that PAGE and SPOOL areas be placed on DASD
devices dedicated to this purpose.
DB2/VM and SFS can use Dataspaces meaning that CP's paging routines are u
sed
to perform the I/O.
Q1. PAV is indeed of no use then. (Most of the VM I/O at my client's
installation are from DB2 and we would be sorry).
DB2/VM and SFS also use IUCV *BLOCKIO to perform I/O
Q2. Can these I/O profit of PAV? (I guess they can)
Kris Buelens
