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memory compatibilities with alphaserver DS25

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F. Javier Cobas
Occasional Advisor

memory compatibilities with alphaserver DS25

Hi all,

I need to add some memory to an Alphaserver DS25 from 1 GB. to 2 GB. for a few days, provisionally.

The memory modules inside DS25 are branded as "Infineon HYS72V16100WR-7.5 E", (8 modules of 128 MB. each, sync, 133 Mhz., CL3, ECC, REG ).

We have around here the following HP/Compaq Alphaserver/Workstation models from which (maybe) we could extract some memory for a while:

* DS20E 667Mhz. EV6.7 --> 4x 256MB. Toshiba T8Z78A-80 inside. (4x 256 MB., Sync, 100 MHz., CL2, ECC)
* DS20E 834 Mhz. EV6.8AL processors.
* DS20E 1000 Mhz. EV6.8CB
* ES47 1000 Mhz. EV7 processors.
* XP1000 with EV6 at 500 MHz.

Anyone can help to find out which one is compatible?. Is there a matrix of memory compatibilities between Alpha Servers/W.S.s?.


Hein van den Heuvel
Honored Contributor

Re: memory compatibilities with alphaserver DS25

DS25 Memory Configuration Rules
Up to 16 DIMMs can be installed.
An Array consists of 4 DIMMs.
Fill Arrays in numerical order.
Populate all 4 slots in Array 0, then populate Array 1, and so on.
DIMMs in an array must be the same capacity and type.
Stacked and unstacked DIMMs can be mixed within the system, but not within an array. The DIMMs within an array must be of the same capacity and type stacked or unstacked) because of different memory addressing.

CAUTION: Using different DIMMs may result in loss of data.

Interleaved operations reduce the average latency and increase the memory throughput over non-interleaved operations.
With one memory option (4 DIMMs) installed, memory interleaving will not occur.
For 2 way interleaving, array 0 & 2 and 1 & 3 must have the same size memory.
For 4 way interleaving, array 0 through 3 must have the same size memory.

The output of the show memory command provides the memory interleaving status of the system.
P00>>> show memory
Array Size Base Address Intlv Mode
--------- ---------- ---------------- ----------
0 4096Mb 0000000000000000 2-Way
1 1024Mb 0000000200000000 2-Way
2 4096Mb 0000000100000000 2-Way
3 1024Mb 0000000240000000 2-Way
10240 MB of System Memory

The show memory display does not indicate the number of DIMMs or their size.
Array 3 could consist of two sets of 128 MB DIMMs (eight DIMMs) or one set of 256 MB DIMMs (four DIMMs). Either combination provides 1024 MB of memory.
For optimum memory utilization and performance, load memory arrays in the following order: 0, 1, 2, and 3.

Only the following DIMMs and DIMM options can be used in the DS25 system.
Density DIMM DIMM Option (4 DIMMs per)
128 MB 20-01CBA-09 3X-MS350-CA (512 MB)
256 MB 20-01DBA-09 3X-MS350-DA (1 GB)
512 MB 20-01EBA-09 3X-MS350-EA (2 GB)
1 GB 20-00FBA-09 3X-MS350-FA (4 GB)

I suspect that only ES45 memory is compatible, but will gladly be proven wrong.

F. Javier Cobas
Occasional Advisor

Re: memory compatibilities with alphaserver DS25

Thanks for the reply.

From the labels in DS20E and DS25 memory module i can see now what seems to be a major difference:

DS25 memory is marked as "REG", while DS20E is not. "REG" memory is not mixable with non-REG one, (at least in the same array banks (?)).

My question now:

If i just tested DS20E or ES47 memory modules in DS25 next pertinent array banks ... is there any risk that the mainboard or the memory modules (or both) could be then damaged as a result?.

[Not doing it, if not completely sure].