Using the thicker 15mm variants with passive heatsink fins helps. But if you got a case where no airflow is flowing through your 2.5" mounts, that’s a problem.
The U.2 cables I’ve seen all use bog standard SATA power connector. Nothing you can’t solve with Molex ↔ SATA
I’m not aware of any drive requiring that. You may need a HBA to get SAS connected. But no SAS = no SAS controller needed.
Thanks for the detailed guide, much appreciated.
I have one of the Samsung 870 Evo QVO 8TB drives. I like it a lot. You are correct that the write speeds are atrocious. This is NOT a drive for heavy IO. Instead this drive is fantastic for write-once-read-many usages.
Another unsung benefit of this drive, is that as far as I can tell, its the largest capacity 2.5" drive on the market. Well, barring clones from the likes of TeamGroup, etc…
What this means is that this drive lets you pack 8TB of space into a single 2.5" drive slot. Not even a 2.5" HDD can do that. Guess what kinda computer thrives on a single 2.5" slot? Intel NUC 
this drive is perfect for maxing out the capacity of your laptop or other mini PC device that has a single 2.5" SATA slot. Note that you will likely want to use a different drive as your boot drive, and use this one for mass storage.
This is a good option as well, I have one of these two and like it a lot, I got mine from Server Part Deals (they have eBay, Amazon, and web store fronts), but keep an eye on the prices, they have been fluctuating, as low as ~$380 or lower even over the past couple months.
dumb question though; wouldnt any sort of array made from a large number of U.2 drives eventually run up against PCIe lane availability limits? You can attach a seemingly limitless number of SATA drives, but PCIe does not seem to be as feasible for large arrays or even just large number of drives. Is it??
Your talking about the Samsung EVO drives, right? I don’t think they ever made a 8TB Evo SSD.
You can theoretically run U.2 drives off of only 1 PCIe lane which would make them just as numerous as SATA ports on any modern raid card; IE a card that supports 32 SATA HDDs will also support 32 U.2 NVMe drives.
I think the problem with this is that people don’t understand what cables they need to buy to attach the U.2 drives correctly.
Oops I had the wrong model, its the Samsung QVO 8TB, this one;
it was down around $300 earlier this year; keep an eye on CamelCamelCamel for the price drops
I’ve been watching samsung pm883 prices like a hawk, They make a 8TB SATA version that runs on TLC NAND but the prices are still too high for me.
you mean something like this?
thanks for the tip, I was not aware that Samsung made other enterprise grade SATA SSD’s
Yeah, that’s it; there’s also a pm983 that’s alittle more expensive.
Their enterprise offerings are alot better than their consumer, at least in terms of TBW, long term data retention, PLP and performance consistency.
Threadripper Pro is the secret.
See here → Gigabyte MC62-G40 - #3 by dazagrt
One caveat though, the cable you linked (and many similar) only carry the SATA signals, just like a regular SATA cable would, but with the SAS form factor. SAS can work off those signals alone, but you’re missing half the theoretical bandwidth and some SAS features (AFAICT, I’m not an SAS expert). You can see it only has two differential pairs instead of four (even though the connector likely has pins for all of them).
Instead, you can look for backplanes or drive cages with SAS backplanes, those typically have SFF-8087 (internal) or SFF8088 (external) connectors and can use all available bandwidth.
That’s pretty interesting. Any way I can verify/validate this is the case without relying on bandwidth testing? My SAS-6Gb drives are all mechanical spinning rust, so there’s no real way to verify bandwidth with those, as they top out around 100~150MB/s on a good day.
The card reports all the drives to be running at 6Gb link speed, though, and that’s what the card tops out at too. Is 4pair for SAS 12/24Gb? and 2pair for 1.5/3/6, or would I only actually be able to get 3Gbit out of this SAS card using these cables?
SAS 3/6/12/24 can all achieve their rated bandwidth without resorting to dual link. Dual link SAS connections just double the nominal bandwidth assuming you aren’t running them in the redundancy oriented dual path configuration. For example a SAS-4 SSD can achieve ~4.5GB/s when running dual path, twice the rated bandwidth of SAS-4.
Running a backplane with an expander will actually decrease your performance due to extra latency it adds to all your data requests.
I gave up on high capacity SSDs and just bought double the amount in 4TB SSDs for my NAS. 6 Samsung 870 Evos costed me just as much as 3 870 QVO but they’re equipped with much better quality NANDs.
NVMEs require too much energy and connectivity to be ran. That’s why I didn’t go that route. Beside being stupid expensive per TB. Also, in my case, I’d have no way to recover the array because I don’t have a system with lots of PCIe lanes.
If you need 12TB of raw SSD space get four good quality SATA drives and be on your way.
If you’re asking about how many signal pairs in the cable, you can tell that from the photo - each of those silver-blue “strands” is a single differential pair.
If you’re asking about performance, I’d say you still should validate bandwidth empirically, especially with those Chinese cables (I’m pretty sure the ones you linked are just resold from AliExpress, e.g. https://www.aliexpress.com/item/1005005817038894.html)
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