Dell EMC PowerEdge R940xa Server ReviewNovember 14, 2019
Just like the other R940 system, the Dell EMC PowerEdge R940xa server also supports up to 6TB of memory and has expanded again to a 4U height on the XA version, basically like the older R930. It supports up to four full-height, full-length GPUS from Nvidia instead of just two, like on the other four-socket platform, the 2U R840. What is this system good for? Artificial intelligence, machine learning, online transaction processing and other high-performance computing applications.
“Dell says this system accelerates applications to deliver real-time decisions, which basically means this system is really fast.”
As an alternative to those four GPUs, you can also install up to eight Field Programmable Gate Arrays or FPGAs. In other words, FPGAs allow you to program a specific function or functions into an FPGA unit, which is kind of like a programmable GPU. Furthermore, FPGAs help accelerate compute and are at the core of many specific applications for automotive, aerospace and defense, medical, and wireless infrastructures.
The storage on the front of the chassis features 32x 2.5-inch storage bays, with 24 bays on top and eight more in the lower portion of the chassis. An optional security bezel is available including one with an integrated LED panel for system status. Additional configurations include an 8-bay, a 24-bay, and an option to install up to four direct-attached NVMe drives in certain configurations.
On the right, there are two USB slots including a micro-AB USB slot for direct access to iDRAC. You’ll also notice a system ID status LED in the upper left-hand corner of the chassis. This provides health status for hard drives, temperature, power, memory and PCIe slots. An optional Quick Sync 2 control panel has the ID status LED and another button for Quick Sync 2. QuickSync 2 lets you access iDRAC directly at the chassis using a smartphone or tablet outfitted with Dell’s OpenManage Mobile app.
The supported drives include SATA, SAS, and nearline-SAS HDDs and SSDs plus up to four direct-attached NVMe drives providing low-latency. The drives on the Dell EMC PowerEdge R940xa plug into the backplane, which is then routed through a SAS/SATA expander and connected to a single PERC H730P RAID controller. NVMe drives are not supported on this configuration, but if they were they would go in slots 20-23 on the front of the system and connect to the motherboard using the 2x PCIe connectors on the lower left portion of the upper backplane, which in turn plug into two PCIe slots on the motherboard.
You can also go with a dual PERC configuration with one controlling the lower drive bays and the other controlling the upper drive bays. For configurations of just eight drives, the integrated S140 software RAID controller can do the heavy lifting without the need for a SATA/SAS expander board. There are more configurations to address specific workloads.
On the back of the chassis are a few USB ports, a dedicated RJ-45 port for remote and at-chassis management using iDRAC, and a few other ports. A slot in the lower left is for a network daughter card offering 1, 2 or 4 ports with different connection speed options including one with four 10Gb Ethernet ports, plus another with two 25Gb Ethernet ports. Of course, you can add more network connections using a few of the potential 12x Gen3 PCie slots. Four hot-plug power supplies on the back of the system provide power and can support 2+2 redundancy. There are four options for Alternating Current and one for Direct Current.
Inside the chassis, six large hot-swap fans provide the cooling. You’ll also notice the black plastic cowling to direct air flow over the critical components. The upper portion channels air to the PCIe slots where you may have four GPUs accelerating compute. However, if you only install two GPUs, you will need a GPU blank for the missing units. The lower portion directs fresh air specifically over the processors and memory plus a little shroud that funnels fresh air over the Network Daughter card.
With the 4U R940xa, all processors are on the same circuit board, which is very different from the 3U R940 we reviewed a few weeks back featuring a separate processor expansion module or PEM for CPUs 3 and 4. You also don’t have any of those strange memory card riser books like on the R920 and R930. Although, the R930 did support up to 12TB, but with slower Xeon E7-4800 V3 or e7-8800 V3 or v4 CPUS that only supported 4 memory channels each.
Up to four Intel Xeon Scalable processors from the first or second generation can be installed. This system requires Gold or Platinum processors because with three Ultra Path Interconnects instead of just two like on the Bronze and Silver families. Each processor also supports six memory channels with two memory modules per channel. Maximum memory is up to 6TB using either Registered or Load-Reduced memory modules. You can also install up to 12 NVDIMM modules along with up to 36 RDIMMs for 384GB of non-volatile memory, but you will need to install the NVMe battery.
A slot on the fan shroud supports the NVDIMM battery used to power the NVDIMM modules for up to a minute in the event of a power failure. NVDIMM memory modules offer greater resiliency with their ability to quickly store active data in an on-board flash memory module in the event of a power failure, a great feature for online transaction processing.
“Once the power is restored, the system determines the most current data and stores the data accordingly.”
The R940xa comes with iDRAC9 Basic, but for more functionality you could also go with Essentials or Enterprise, which has all sorts of ways to efficiently manage your system at the chassis and remotely. With iDRAC9 you also get the Lifecycle Controller, which as the name would suggest it helps you manage the system over its lifecycle. The Dell EMC PowerEdge R940xa offers advanced embedded management capabilities like deployment, configuration, maintenance, diagnosis, and updates both at the chassis and remotely. This is also where the Quick Sync II comes into play which provides at-chassis management using a smartphone or tablet through a secure bluetooth connection, but only if you have the optional control panel with Quick Sync. Dell’s OpenManage management suite provides even more tools for managing and deploying server assets across a data center and supports several generations of Dell servers plus third-party appliances.
The number of available PCIe slots on the Dell EMC PowerEdge R940xa depends on your choice of risers to outfit the system with a total of 12x PCIe 3.0 slots possible. In our case we have two risers that support two x16 slots for two double-wide cards and a single x8 slot. It also has three SATA/SAS connectors. Another optional riser supports up to 10 Network cards. In addition to the storage controller options, GPUs or FPGAs, you have other choices for network connectivity using the PCIe slots, and that’s in addition to the network daughter card options we already discussed.
There are many options for PCIe cards to increase network communications speeds including 100Gb Melanox and Intel Omni-Path options also supporting 100Gb network communication speeds. Bifurcation of the PCIe lanes is also supported, providing more options for additional storage and networking. That means for one of these PCIe lanes instead of a x16 lane, we could break that into two x 8 lanes or four x4 lanes running in parallel. Bifurcation is a necessity if you plan on installing FPGAs to address specific workload specific applications.
A BOOS or Boot Optimized Storage Subsystem PCIe card with dual M.2 drives can be used to boot the system without using any of your upfront drives. There’s also a dedicated slot for an optional micro SD card module for a hypervisor. It supports two micro SD card modules on one side that can be used in mirror mode for redundancy and a single flash card on the other that can be used by iDRAC for storing disk images and updates. A toggle on the card is for write protection.
In short, Dell makes some pretty beastly hardware. The Dell EMC PowerEdge R940xa is a 4-socket powerhouse that is highly adaptable to a number of business applications. It offers a 1:1 relationship of CPU to GPU to accelerate performance. Outfitted with optional GPUs or FPGAs you have even more options for configuring your system to support your unique workload.
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