UltraSPARC-T2+ Servers Announced!

Today was a big day! Sun announced the T5140 and T5240 servers which are the first dual socket UltraSPARC-T2+ CMT servers. This means that you can now scale out to 128 threads in a 1U and 2U form factor! The UltraSPARC-T2+ processor is a little different from the UltraSPARC-T2 processor. Here are some of the differences:

• SMP enabled
• Coherency links to support SMP
• Only 2 FB-DIMM Memory Controllers instead of 4
• Relaxed DMA ordering
  
• Removal of the 10GbE Controller from the processor
  

As you can see, the ability to support SMP required some extra room on the processor. The coherency links provide the glue to enable SMP between UltraSPARC-T2+ processors. The number of FB-DIMM memory controllers is cut in half, but the ability to address a larger amount of RAM is enabled. The 10GbE controller is removed, and supplemented by a Neptune ASIC on the mainboard to manage the XAUI ports and the four onboard 1GbE ports. Altogether, not a bad compromise to support SMP. We still have the same number of cores and threads per chip, with the added benefit of having two chips!

The T5240 has the added benefit of double the number of physical RAM slots thanks to a mezzanine board that plugs in over the mainboard. We also see double the amount of disks on the T5140/T5240 from the T5120/T5220. This definitely allows a greater number of disks to be used for LDoms! Also, the other big change is in I/O. We have two PCI-E controllers, one in each CMT chip! We also have PCI-E x8 lanes across the board. This is an improvement over the T5120/T5220 which only had two x8 slots and four x4 slots. This increases the bandwidth available for pushing I/O. Here is a great blog entry on the subject.

Speaking of LDoms, we now have 128 threads to work with! Obviously, you'll want to use LDoms 1.0.2 to support these systems. Considering that once the control domain is configured, we still have 15 cores (120 threads) to work with for guest domains. Even if one were to break each core up into four guest domains, that's 60 guest domains! Performance wise that would probably be the smallest configuration you would want to go since each core has two execution units (each handles 4 threads). Any smaller and one would risk cache thrashing. Added with the ability to have 64GBs or 128GBs of RAM, one can definitely take on larger apps. I'm curious if a split PCI-E configuration can be achieved with these servers and if there is any benefit? Still this is very impressive for a 1U/2U form factor with such a small physical footprint.

Wish I had one of these to play with already! It would be fun to write a review of a T5140/T5240 server!

The next system of interest will be the T5440, which will be a four way UltraSPARC-T2+ system. That has to be a beast of a box!