I am TOTALLY Confused with vSphere 5.0 Enterprise Plus Licensing Model and the Memory Configuration on Dell Poweredge R720
Say if I have ordered the latest Dell Powerdge R720xd with 2 sockets Xeon-E5 CPUs and fill it up with 768GB Ram (32GB x 24 Dimms). R720 supports 4 memory channels per processor, that’s 3 dimms per channel, so 12 dimms in total per processor, or 24 dimms per 2 sockets. In contrast, R710 supports 3 memory channels and 3 dimms per channel, a total of 18 dimms per 2 sockets.
Since vSphere 5.0 Enterprise Plus Licensing Model allows 96GB vRAM per socket, so that’s 192GB vRAM per the above configuration, this leaves the remaining 576GB vRAM in question. According to their licensing formula, I need to purchase 6 more EP licenses in order to fully use the 768GB Ram. Sounds strange that I need to have 8 CPUs license while the physical server only has 2 CPUs.
Let’s put the above extreme case aside, in reality not many is going to order that super expensive 32GB and no one is going to put that much ram in mid-range server like R720 as well anyway.
So let’s focus on the optimal memory configuration for R720, I would say it’s most likely to be 192GB (in fact 256GB).
Currently, mainstream is still 8GB ram, therefore for 192GB RAM, that’s 24 Dimms (8GB x 24), but with 3 Dimms Per Channel (DPC) configuration, it will decrease the RAM speed to 1066Mhz which I want to maintain RDIMM at 1333Mhz bandwidth and 1.35V, so in order to do that, I can only use 16GB ram and for 192GB, that’s 12 Dimms, an uneven number configuration, 3 channels per side, missing one channel, this sounds REALLY ODD?!!! Isn’t it a big drop in memory performance if we do not fill up all channels on each socket? (I might be wrong on this)
So if I insist to run at 1333Mhz, the only choice I have is to have 2DPC x 4 channels, that’s 16 Dimms x 16GB = 256GB, well, it’s over 192GB limit!
I really don’t know what else I can configure the memory in order to fully use 256GB ram with 2 VMware EP license. If you have any better suggestion, please let me know. Of course, if my assumption of fully using all 4 channels proved to be wrong later, then this won’t be a problem.
That’s why people are suggesting VMware to raise the bar to 128GB per socket, this would be perfect solution then, let’s see.
Oh…I just noticed NASDAQ:VMW had a free fall on Wed as their CFO jumped off the ship, is something going on under the table?
I agree it should be 128GB/socket minimum, especially with 8-core CPUs and the falling price of RAM. Note that you might as well get it with 256GB RAM (at least, probably more), because you are only licensing what you are using per VM, not what is physically in the server, and that amount goes across the vCenter. So when you are doing maintenance, you’ll want more memory than you use per host regularly, as those VMs migrate from host to host. Plus you want some memory for host overhead. And also more memory for short tests, clones, whatever. “The 365-day moving average of daily high watermark of vRAM configured to all powered-on virtual machines in aggregate cannot exceed the pooled vRAM capacity.”
“The vRAM entitlements of VMware vSphere processor licenses
are pooled—that is, aggregated—across all CPU licenses managed
by a VMware vCenter instance (or multiple linked VMware
vCenter instances) to form a total available vRAM capacity
(pooled vRAM capacity)” from http://www.vmware.com/files/pdf/vsphere_pricing.pdf
Oh…I forgot vSphere 5 allows license to float across servers, so this won’t be a problem a long as my average 365 days concurrent vRAM total is within the vRAm pool limit, it doesn’t matter my host is having 192GB or more.
Your reply actually solved my confusion, thanks.
In another words, the new license somehow makes a bit of sense now.
Not related with licensing – but be careful if using 192 GB RAM, as it would not run @1600 MHz if populating all DIMMs per channel.
Please refer to http://www.poweredgecpumemory.com/
On the licensing topic, it seems ESXi 5.1 will finally get rid of “vTax” so this is good news.
That’s really an interesting web site, I do find it’s very useful, thank you very much!