Exadata Memory Expansion Kit
Dec 2, 2011 / By Marc Fielding
I was just looking at an Exadata X2-2 ordering document and noticed that it included 144GB of RAM. The sales rep pointed at the Exadata X2-2 datasheet and showed the 96GB to 144GB memory expansion option. Based on my reading of Intel Xeon (Nehalam) memory configurations, as long as each channel has a single dual-ranked module, all the memory can run at full 1333MHz speed. (Update: as noted in the comments, this is unfortunately not the case in Exadata; with the expansion unit memory runs at 800MHz). It populates the normally-empty third socket for each memory bank with an additional memory module.
It isn’t particularly cheap: $6250 per database node at US list price, but is a performance booster that doesn’t have ongoing support costs either. For OLTP environments, I like to say cache is still king, and even for those of you with pure data warehouses, 50% more PGA space can help out your sorts too.
And yes, I realize this isn’t particularly new; according to Kerry Osborne’s blog it came out (but wasn’t officially announced per se) at the same time as the storage expansion racks in the summer
If you use the expansion kit and fully populate all the slots, the frequency of the memory DIMMs drops to 800 MHz from 1333 MHz. This is mentioned in the blog post you site as well.
Confirming Greg is correct…
Since cache is king :-) we have used the memory expansion kit
[oracle@exa52db01:PJT5]/dbfs/fs52/prod_dba => cat /proc/meminfo | head -1
MemTotal: 148294940 kB
Handle 0×0055, DMI type 17, 28 bytes
Memory Device
Array Handle: 0×0048
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: 8192 MB
Form Factor: DIMM
Set: None
Locator: D3
Bank Locator: /SYS/MB/P1
Type: DDR3
Type Detail: Other
Speed: 800 MHz
Manufacturer: Samsung
Serial Number: 829FC09B
Asset Tag: AssetTagNum5
Part Number: M393B1K70CH0-YH9
Rank: 2
On machines on which we have not used the memory expansion kits the frequency is 1333 MHz
Thanks guys – I’ve run into this memory-speed limitation in non-Exadata Xeon-based systems, and was wondering if Exadata had the same restriction, but couldn’t find clear docs either way. Even at 800MHz though, I’d take the 50% additional RAM :-)
Marc,
I think you mentioned Kerry Osborne’s blog, but gave the link to Andy Colvin’s blog.
Thanks to Greg for pointing out about the drop in memory speed. I certainly did not know about it.