Memory installation rules for RP7420

[Carl Houseman]

In this document:
http://docs.hp.com/en/A7025-96018/ch01s02.html

under "Valid Memory Configuration", it says:

"The DIMMs across all cells in a partition should have identical memory loaded."

What does that mean exactly? This RP7420 has 2 cell boards, the first populated with 4 x 4 GB modules, the second half-populated with 2 x 4 GB modules. I'd like to add 2 x 8 GB modules to the unpopulated quads in the 2nd board. Is that a valid configuration?

[Prashanth.D.S]

HI Carl,

Find the memory loading order for RP7420

DIMMs must be loaded in sets of two at specified locations on the cell board. Two DIMMs are called a rank, so two ranks would be equivalent to four DIMMs, three ranks would be six DIMMs, and so on. The DIMMs must be the same size in a rank. The DIMMs across all cells in a partition should have identical memory loaded.

DIMM Load Order Number of DIMMs Installed
Action Taken
DIMM Location on Cell Board
Quad Location

2 DIMMs = 1 Rank
Install First
0A and 0B
Quad 0

4 DIMMs = 2 Ranks
Add Second
1A and 1B
Quad 1

6 DIMMs = 3 Ranks
Add Third
2A and 2B
Quad 2

8 DIMMs = 4 Ranks
Add Fourth
3A and 3B
Quad 3

10 DIMMs = 5 Ranks
Add Fifth
4A and 4B
Quad 0

12 DIMMs = 6 Ranks
Add Sixth
5A and 5B
Quad 1

14 DIMMs = 7 Ranks
Add Seventh
6A and 6B
Quad 2

16 DIMMs = 8 Ranks
Add Last
7A and 7B
Quad 3

Best Regards,
Prashanth

[Carl Houseman]

Reciting the memory ordering table from the docs doesn't really help at all.

I want this question answered (restating):

In my RP7420
- two cell boards
- one nPartition
- 4 x 4GB on cell board 1
- 2 x 4GB on cell board 2
- 2 empty quads on cell board 2

May I install 2 x 8GB modules into the 2 empty quads on cell board 2?

The documentation says I can mix DIMM sizes within a QUAD as long as the DIMMS in a single RANK are the same size.

The permitted size mixing does not seem to agree with the statement "the DIMMS across all cells in a partition should have identical memory loaded".

What is "identical" ? Same size? Same manufacturer? Same everything?

"Should" I throw away all of the 4GB modules if I wish to use any 8GB modules?

And can I take the "should" as a recommendation and not a requirement?

[V.Manoharan]

Hi Carl Houseman,
You can have mixed sizes of memory in different quads. But as per your requirement the 8 Gb module will not be supportable in rp7420. The below are the supported memory modules in rp7420

A6098-69101 --1GB high-density SDRAM DIMM (single DIMM)
A6098-60101 --New part for A6098-69101
A6100-69001 --2GB high-density SDRAM DIMM
A6100-67001 --New part for A6100-69001
AB322-69001 --4GB high-density SDRAM DIMM (four 1GB DIMMs)
AB322-67001 --New part for AB322-69001
A5198-69101 --512MB high-density SyncDRAM DIMM memory

Note : If you order for 8Gb memory for rp7420 you will get 2Gb * 4 Modules not single 8Gb module.

Thanks and regards
V.Manoharan

[Carl Houseman]

I'm still looking for someone to refute the statement ""The DIMMs across all cells in a partition should have identical memory loaded."

Or at least say what that statement intended to mean. You can't have "identical" memory in all DIMMS and different sizes in a quad.

If you can't tackle that question there's no need to reply.

And when I said 8GB module I knew that A6100A consisting of 4 x 2GB DIMMS.