DB2 9 Memory Requirements
MartinPacker 11000094DH Visits (3910)
Twice the "128GB" question has come up in newsgroups (the latest in DB2-L). This sort of thing freaks people out - so let me tell you what I know of the matter...
So, in DB2 9, the interface between DDF and DBM1 was radically redesigned: Now the communication is done using a z/0S 64-bit Large Memory Object. This is in Virtual Storage above the 31-bit bar. When the DBM1 address space starts up this Large Memory Object is allocated with a 128GB size. Communications take place between DDF and DBM1 using this area: But we're not talking about data moves and reformatting anymore. So this should cut the CPU. (And it also removes the constraints I mentioned above.)
There are two key points here:
I should also point out there will be some Virtual storage savings - below the 2GB bar. That will be welcome to a number of customers I know. (And I may well blog about this soon.) But one caution:
I do not expect the need to manage thread numbers and thread footprints to go away, perhaps ever...
DB2 9 does not move the whole thread footprint above the bar. And threads still cost Real memory - though it would take many thousands to have an impact on memory capacity planning. You do do memory capacity planning, don't you?