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Diablo MCSDuring VMworld we had the opportunity to sit down with Ricky Trigalo en Kevin Wagner from Diablo technologies to talk about their storage solution called “Memory Channel Storage” (MCS). Basically this means that you insert NAND flash memory into a memory bank instead of your standard memory DIMM’s. Is this the way of the future or the way of the dodo?

Diablo Technologies is a long standing company that is specialized in developing high speed memory systems. A little over 3 years ago they started working on MCS together with IBM. At the moment they are the only company who design and deliver MCS. For the storage subsystem Diablo Technologies is in collaboration with SanDisk. SanDisk delivers the controllers / FTL (Flash Translation Layer) and their Guardian Technology for the endurance.

Developing a solution like this requires a lot of in depth knowledge about memory systems which generally can only be found with memory producers. As to why other memory producers normally would not look at this, is because most memory vendors see flash as a slow solution compared to normal memory. From a technical standpoint, this is correct.

Diablo DIMM

But the flash market is booming and running into bottlenecks at the architectural level inside the server. The SAS/SATA bus can’t deliver more than 6Gb/s. NVME solutions like FusionIO or Violin have more bandwidth but less queue depth. This means that 1 IO is processed very quickly, but big streams with lots of IO clog up the bus and the performance goes down, according to Diablo. This is where MCS comes in.

MCS benefits from the huge bandwidth the memory bus has to offer, the proximity to the CPU’s of the server and the higher clock tics. Through NUMA technology it can be accessed very quickly by the system. Technically it requires a (U)EFI BIOS in the server for it to function, but not alot more than that. The modules come in 200GB or 400GB per module. Plugging 4 modules into a server will deliver you 1.6 TB of ultrafast flash storage.
Diablo Paralel Bus

The Storage is offered as a single LUN to the ESX server through a kernel driver. This means that when used in combination with vSAN, your host will have one big flash disk available. With a traditional storage solution, vSAN would only be able to use the first single flash based (small) disk in a host, supplemented with SAS / SATA disks to get a higher capacity.

As vSAN benefits from MCS so does MCS benefit from the use of vSAN. MCS at the moment only has the option to use RAID-0 and thus has no fault tolerance. With the use of vSAN the hosts used will provide the fault tolerance. Diablo did indicate that requests where made to put in other RAID configurations, these requests have been taken seriously and they are working on a RAID-10 configuration.

Currently Diablo sees their main advantage in VDI and Database deployments. Swapping of VDI sessions to flash storage will, in the case of MCS, result in no performance impact of the session as the storage is still very fast and a copy action from memory to ‘disk’ is down through the RAM bus and not through an HBA over PCI Express lanes. But of course DBA’s will also become very happy from storage with only several microseconds of response time (MICROseconds, not MILLIseconds).

Diablo data traffic

Currently IBM (Lenovo) and Supermicro are offering MCS in their systems, but more OEM’s are in the pipeline and should be introduced shortly. For more information see the Diablo technologies website. It looks very promising and the innovation and idea are very good to bring the storage even closer to the CPU.