I bought two Viking U20040 U.2 to 4X M.2 carriers, and I just wanted to add some notes for those considering getting these since I couldn't find much information about them online.
Top and bottom M.2 slots with loaded inland 2280 1TB drives. Notice on the top left shot it has one capacitor. (PLP?)
Size comparison with an HGST HUSMM8040ASS20 on the left and an intel DC S3520 on the right.
PCIe Topology
- These carriers can only accept 2280 M.2 drives.
- It uses a Switchtec PM8531 PFX PCIe Gen 3 fanout switch. So, x4 PCIE Gen 3 speeds are the maximum throughput per carrier.
- It takes 4 PCIe lanes and provides two lanes to each M.2 through the switch.
- The entire frame of the drive is metal and acts as a heatsink.
- The carrier alone uses around 7-8 watts. Measured at the wall with a kill-a-watt.
- Can get quite hot. It needs some air flow. (temperatures to come soon)
- It also includes a management interface for the PCIe switch where you can monitor the U.2 Carrier statistics and configuration. There's a driver that needs to be installed and user tools that need to be built to use it in Windows. This driver isn't required for normal operations.
Adding more than one of these carriers will cause a resource issue with the management interface because they want to use the same memory ranges. Doesn't affect normal operations. I disabled it on the second device since I'm not using it. This seems to be more of an issue with the Dell T7820 rather than the carrier. Should be ok in other systems.
- Apparently, there’s a driver to enable dual-port support for HA applications. It partitions the drive into (2) 2 lanes, allowing two different systems or CPUs to access it. I’m unable to find more information.
- The brochure mentions it has PLP, but I'm not sure the carrier itself does. Needs some testing. (I could use some pointers to test this)
- You don't need to populate all M.2 slots.
- Each drive is presented independently. These do not do any JBOD or raid on their own. Just in case someone was wondering...
I did some quick benchmarks using CrystalDiskMark with two different brands and configs.
(4)
Optane p1600x 58gb
With a single drive, it was very close to the limit of the 2 PCIe gen 3 lanes provided to it in sequential reads and the limit of the drive itself for writes. Random reads and writes were excellent as well, with low access times, but that's just Optane flexing its muscle.
Adding a 2nd drive in a stripe doubled sequential reads and writes. Random reads and writes at higher queue depths presented a slight improvement. No doubt the full 4 PCIe lanes are being used in this case.
Adding the 3rd drive didn't do much for sequential reads as expected due to the 4 PCIe lanes on the U.2 interface. Sequential writes saw another decent boost. Random reads and writes saw very little change. I chalk that up to a margin of error.
Adding the 4th drive pretty much maxed out the bandwidth of the x4 interface with sequential reads and writes. Again, the random reads and writes saw very little difference. Infact, random Q1T1 barely changed at all in all 4 tests.
(4) Inland (Microcenter Brand) 1TB using a Phison E12.
I striped all 4.
Sequential read and writes pretty much maxed out the 4 PCIe lanes.
Random reads and write speeds are normal. No anomalies were noticed.
Some interesting ideas on what to do with these carriers:
- Using an M.2 to U.2 adapter to have 4 SSD drives on a cheap consumer board without using other slots.
- Putting four of them on a PCIE x16 card with bifurcation enabled to have 16 drives on a single PCIe slot.
- Or, like in my case, having eight drives on my Dell Precision T7820 using only the two front NVME U.2 drive bays, leaving the PCIe slots available for other uses (Had to increase airflow on HDD zone by 30% in bios).
So far, I think the Viking U20040 is not bad if you're looking into more density rather than performance. Sure, having dedicated PCIe lanes to each SSD would be excellent for performance, but that's not always possible or needed.
Dang, this post went longer than expected. Hope it helps others who like me were looking into more information about this carrier.
*****EDITS*****
Added more clarity.
Corrected inland drive Phision model is E12, not E15.
Finished testing inland drives outside the carrier. Latency behavior was the same.
Added power consumption.
Added information about heatsink.
Corrected typo on Dell Precision model number. T7820, not T5820.
Added product pictures, size comparison and pcie layout.
Added warning about airflow.
Added Benchmark pics and updated text about benchmarks after proper testing with single CPU.
Found reason for device conflict when more than one carrier added.
****TO DO****
Build user tools to monitor carrier stats and temps. Tools don't seem to work for gen 3 devices in windows.
post driver, brochure, and user tools if possible.