One of the more exotic thing Minisforum do with their machines is the support of SSDs in the form factor of U.2, which is usually only seen in enterprise hardware. They started doing this with the MS-01 with support of one U.2 slot, and recently they upped their game even more with the N5 Pro with two U.2 slots.
After I got my MS-01, I immediately decided that I wanted to go all the way and get the largest drive there is to put in it. Now you would think that the monstrous Solidigm P5336 at 122.88 TB would fit the bill quite nicely. (The even larger Kioxia LC9 at 245.76 TB is of the E3.L form factor.) However, not all U.2 are the same. Despite all being 2.5”, they come in two heights: 7mm and 15mm.
MS-01, unfortunately, can only fit the 7mm U.2 form factor unless you modify the chassis. So, I had to settle for the largest 7mm U.2 drives(also because I cannot afford the Solidigm one), which are at the size of 15.36 TB.
There are only two drives that meet this criterion: Samsung PM9A3 and Micron 7450 PRO(U.3 backwards compatible). Ultimately, I took the advice of a r/homelab Discord member and chose the Samsung PM9A3.
I could buy a new one at 2389 USD from Supermicro, but what most people in the homelab community do when it comes to enterprise gear is they find a used one, usually ripped from decommissioned servers, because they’re often much cheaper and could still be in great shape.
I searched around and found there are quite a number of listings of used PM9A3 on Xianyu, which is basically Chinese eBay and is run by the same company as Taobao and AliExpress. I kept tabs on the prices on there for about a week and found the average going rate was around 8000 RMB(~1114 USD).
I haggled with some sellers and ended up with a deal for a 100% health unit at 7450 RMB(~1037 USD). Btw that was February and I just checked and the same seller is currently selling at 7980 RMB(~1111 USD), so I’d say the market didn’t fluctuate much.
Putting it into the MS-01 is easy enough. You just connect the M.2-to-U.2 adapter that comes with the MS-01 and flip the switch from M.2 to U.2 to ensure the voltage is correct and finally insert the drive. It sits very snug under the fan cover, they’ve clearly utilized all the space available here.
It arrived in March this year, but I haven’t had time to properly test it until recently. I’ve left the machine on nonetheless, so the powered-on hours may have been slightly exaggerated.
System
On CrystalDiskInfo, you can see that there has already been more than 500 TB written. Now on a consumer drive, this could be a big deal. But on an enterprise drive like this, this is but a scuff. PM9A3 is rated for 1 DWPD(Drive Writes Per Day), meaning it should last 5 years if you write to the whole SSD every single day. To convert it to TBW(Terabytes Written=the total amount of data that can be written to an SSD), we do the simple math 15.36 TB * 365 days * 5 years = 28032 TBW. 507/28032 is about 1.8%, so this means this PM9A3 is still very young!
Also, just to give you an idea of how enterprise drives are just built different: consumer drives mostly aren’t even rated with DWPD but with plain and simple TBW. For example, the 990 Pro 2 TB is rated at 1200 TBW, which translates to 1200 / (2 * 365 * 5) ≈ 0.328 DWPD, which is not even one-third of the 1 DWPD of PM9A3.
Here’s HWiNFO for some more information. Note that, because this is probably an OEM drive ripped out of a pre-built server, the official Samsung Data Center Toolkit(Samsung Magician equivalent for enterprise SSD) does not work with it because it rejects its firmware version GDD52W2Q. On their website, Samsung only lists GDC5602Q and GDC5A02Q as supported, which are probably the firmware versions if you buy the SSD from retail.
Performance
The PM9A3 is rated at 6800 MB/s for sequential read; 4000 MB/s for sequential write; 1000000 IOPS for random read; and 180000 IOPS for random write.
CrystalDiskMark test shows about the right performance, except that sequential read is more than 1000 MB/s lower than the spec. The random write is way above the spec, but that’s not unexpected, as the specs are rated for prolonged steady-state performance instead of bursts.
We can achieve peak read speed from the spec using DiskSpd with a smaller block size, higher queue depth, and more threads(SEQ128K Q32T16):
.\diskspd.exe -c128G -d60 -Sh -si -b128K -o32 -t16 -L D:\pm9a3_seq_read.dat
And now we can see the read speed does match the spec’s 6800 MB/s pretty nicely at 6961 MB/s(6638.46 MiB/s).
Thermal
Like most SSDs, its standard operating temp is between 0 °C and 70 °C. Fitting an enterprise SSD that’s meant to be stuffed inside a rack-mounted server with tons of airflow inside a Mini PC does raise the question of thermals. I fully expect it to throttle at some point, but I still did some tests to confirm. First off, the NAND idles at around 57 °C, and the controller idles at around 66 °C.
Using DiskBench to copy a 500 GB folder of randomly generated files, the transfer rate held steady at just over 2 GB/s. The peak NAND temp was 69 °C, while the peak controller temp was 79 °C. This speed was likely bottlenecked by my source drive, which was a Crucial P3 Plus in a PCIe Gen 3.0 x4 slot.
To really stress the PM9A3, I again switched to DiskSpd and ran a 15-minute sequential write test(SEQ128K Q32T16) with:
.\diskspd.exe -c128G -d900 -Sh -si -b128K -o32 -t16 -w100 -L D:\pm9a3_throttle_seq_write.dat
And finally, I was able to thermal throttle it. After around 3 minutes and 45 seconds, it throttled with the NAND temp at around 76 °C and the controller temp at around 86 °C. The write speed dropped to around 2.5 GB/s and sustained at that speed for the remainder of the test. In the end, the peak NAND temp was 79 °C, and the peak controller temp was 88 °C.
Caveats
Although StorageReview gave this drive an overall positive review, HOMOLAB warned about its potential 0E issues(Media and Data Integrity Errors) because it is based on Samsung’s 6th-gen V-NAND(V6).
Put in simple terms, 0E failure is when the NAND chips produce uncorrectable data errors, forcing reallocation of faulty blocks, which consumes spare blocks, and, in turn, increases wear on the remaining healthy blocks. This vicious cycle continues to accelerate until there are no more healthy blocks remaining to reallocate, resulting in total drive failure. Once this irreversible process starts, there’s nothing else to do other than watch it slowly die out.
Conclusion
While putting a 15.36 TB enterprise U.2 drive inside a mini PC may sound crazy, it actually works out quite well. This setup gives me enterprise-grade endurance and performance at homelab scale. This is the first time I bought a used enterprise part, and I had quite a positive experience. Hopefully, this will last me a long, long time.
Appendix
For completeness, here are some more test results for the curious:
I can’t afford PCMark Professional Edition or SPEC Storage Benchmark, not to mention Calypso CTS/IPF 😭 Sorry
Correction
Despite Micron’s vague datasheets, from the looks of vendor listings like ServerSupply, the 7mm version of 7450 Pro only goes up to 7.68 TB, so the Samsung PM9A3 was really the only choice for 15.36 TB at 7mm.