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rp7420 can i have one cell with 4gb dimms, another cell 2gb dimms?

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cartman_2
Frequent Advisor

rp7420 can i have one cell with 4gb dimms, another cell 2gb dimms?

Hi,

I have a doubt, in the memory config rules of the rp7420 they say:

The 16 GB memory modules (4×4GB DIMMs) cannot be mixed with other memory DIMM sizes.Cell boards can contain 4 GB DIMMs or non stacked DIMMs (512 MB, 1 GB or 2 GB), but not both.

So can I have a cell full with 4gig dimms, and the other cell with 2gig dimms.

Ending with something like this ?:

NPAR with 2 cells, mem:

[Memory Details]

DIMM Size (MB) Status

==== ========= =========

0A 4096 ok AB322-60001

0B 4096 ok AB322-60001

1A 4096 ok AB322-60001

1B 4096 ok AB322-60001

2A 4096 ok AB322-60001

2B 4096 ok AB322-60001

3A 4096 ok AB322-60001

3B 4096 ok AB322-60001

4A 4096 ok AB322-60001

4B 4096 ok AB322-60001

5A 4096 ok AB322-60001

5B 4096 ok AB322-60001

6A 4096 ok AB322-60001

6B 4096 ok AB322-60001

7A 4096 ok AB322-60001

7B 4096 ok AB322-60001



0A 2048 ok AB309-60001

0B 2048 ok AB309-60001

1A 2048 ok AB309-60001

1B 2048 ok AB309-60001

2A 2048 ok AB309-60001

2B 2048 ok AB309-60001

3A 2048 ok AB309-60001

3B 2048 ok AB309-60001

4A 2048 ok AB309-60001

4B 2048 ok AB309-60001

5A 2048 ok AB309-60001

5B 2048 ok AB309-60001

6A 2048 ok AB309-60001

6B 2048 ok AB309-60001

7A 2048 ok AB309-60001

7B 2048 ok AB309-60001

2 REPLIES
moonchild
Regular Advisor
Solution

Re: rp7420 can i have one cell with 4gb dimms, another cell 2gb dimms?

Cartman,

You can not mix 4G DIMMs with any other DIMMs on rp74xx or rp84xx.

For best performance and availability, configure nPartitions to meet the following guidelines.

â The number of cells participating in memory interleave should be a power of two, and each cell participating in interleave should contribute the same amount of memory.
â The total amount of memory being interleaved should be a power of two number of GBytes.

The memory configuration of all cells in an nPartition should be identical to achieve best performance.
Each cell in an nPartition should have:
â The same number of DIMMs
â The same capacity (size) and the same locations (population) of DIMMs
This avoids cell interconnect (crossbar) "hot spots" by distributing memory evenly across all of the cells in the nPartition.

The memory configuration of each cell should include a multiple of two memory echelons per cell. Each memory echelon is 2 DIMMs. If possible, install memory in sets of 4 DIMMs: 4, 8, 12, or 16 DIMMs.

This provides a performance improvement by doubling the memory bandwidth of the cell, as compared to having one memory rank or memory echelon installed.
This also can provide an availability improvement, in that if one memory rank or echelon fails the cell still has at least one functional rank of memory.
(Memory echelon 0, must be functional for a cell to boot.)

This is said, you can still have the 2 cells as you described above. But you won't be optimized for best performance.

Hope this helps.
cartman_2
Frequent Advisor

Re: rp7420 can i have one cell with 4gb dimms, another cell 2gb dimms?

So just to make it clear, the configuration I metion above 1 npar 2 cells, cell1 all dimms 4 gigs, cell2 all dimms 2 gigs.

But and it a big BUT, performance would be hit, this is a 7420 with 11.11(no local cell memory), oracle(oltp) How much of and impact would this configuration have on the database performance?