P690 partition 1

[we2aresame]

There is a question on a ibm redbook:
A new p690 with 8 CPUs, 8GB mem, and 2 I/O drawers. Whtat the maximum number of partitions allowable with this size of machine?
The giving answer is 6
I thought that if using 256MB as the memory of each partition, then the maximum possible should be 8.
Any suggestion? Thanks.

 

[unixfreak]

Can you assign less than 1GB?

Cheers

 

[we2aresame]

No limitation from the question. Even using Large Real Mode Memory(>=1G), I thought the answer should be 7, thanks.

 

[admincff]

You must have at least 1 processor and 256 Mb of memory per partition (in AIX 5.1 / 5.2)..
You have at least 4 block of 4 disks by I/O drawer.... Each block can be dissociated.... One block=One partition.

Then in your configuration, you can have maximum 8 partitions....

 

[gilsont]

[tt]

I suspect that the Redbook you refer to is old - the smallest amount of memory you could allocate to an LPAR used to be 1Gb. This would make the 6 LPAR maximum correct - the memory would be allocated like this:

0000Mb-0256Mb For the hypervisor
0256Mb-0512Mb For the Page Table space. As the LPAR memory is 1Gb, each LPAR requires 1/64th of this for page table space. 1/64th of 1Gb is 16Mb. Only one page table space of 256Mb is required as all LPARs can 'fit' into this one.
0512Mb-1024Mb cannot be allocated as partitions with 1Gb memory have to start on a 1Gb boundary.
1024Mb-2048Mb for LPAR 1
2048Mb-3072Mb for LPAR 2
3072Mb-4096Mb for LPAR 3
4096Mb-5120Mb for LPAR 4
5120Mm-6144Mb for LPAR 5
6144Mb-7168Mb for LPAR 6
7168Mb-7936Mb not big enough for any further 1Gb LPAR
7936Mb-8192Mb for TCE (256MB if 4 or less I/O drawers)

Nowadays we can allocate 256Mb to a partition, so we can use all 8 processors and I/O drawer boot disks to get 8 LPARS:

0000Mb-0256Mb For the hypervisor
0256Mb-0512Mb For the Page table space. As the LPAR memory is 256Mb, each LPAR requires 1/64th of this for page table space. 1/64th of 256Mb is 4Mb. Only one page table space of 256Mb is required as all LPARs can 'fit' into this one.
0512Mb-0768Mb for LPAR 1
0768Mb-1024Mb for LPAR 2
1024Mb-1280Mb for LPAR 3
1280Mb-1536Mb for LPAR 4
1536Mb-1792Mb for LPAR 5
1792Mb-2048Mb for LPAR 6
2048Mb-2304Mb for LPAR 7
2304Mb-2560Mb for LPAR 8
2560Mb-7936Mb Free
7936Mb-8192Mb for TCE (256MB if 4 or less I/O drawers)

I hope that clears it up for you.


[/tt]