I've been using a TS-212 just about 24/7 for two years. I was happy enough with it that I recently bought a second QNAP device, albeit one that has 4 drive bays (TS-451). It appears that the TS-212 has been phased out in favor of the TS-231, but the specifications appear to be very similar. I think it will meet your requirements.
Put two or ...
Asus PRIME X399-A
This does support RAID 0,1, and 10
However RAID 1 is kind pointless especially if you use SSD.
Right from the manual
And it supports 2 ssd of the m.2 variety.
You can put any size card in an x16 slot. However, note 2 of the x16 slots operate in x8 mode, but that is still more than x4 card needs.
Lets forget the RAID at least for speed....
You could buy a 4-port SD card hub for ~US$63.
However, you could easily make your own: SD card readers are available for less than $US2, and a 4-port USB hub for ~US$6, so you could assemble a similar 4-SD card hub for
You don't state your purpose, so it's hard to understand what you need.
If you're trying to make copies of SD cards, e.g. as OS for a ...
you can just amazon "external sas".
for example "HighPoint RocketStor 6414S 6Gb/s SAS/SATA 4-Bay Storage Tower Enclosure" for $289.
you are not likely to find anything economical, not with SAS. SAS is server work environment, not for home use. If you picked up a couple sas disks you may want to just cut your losses now if this is for ...
Do devices like these always work nicely together these days?
This depends on the dual-bay enclosure that you buy, but most of them appear to the computer as a USB hub with either one or two USB storage class devices attached to it.
With the enclosure that I have used before (Mediasonic ProRaid), there is a physical switch to select how the disks are used. ...
I'm not sure about their software, but being a company specialising in this presumably QNAP has good software support.
One device which I presume will meet your expectations is the TR-002 which has two 2.5" bays. They even post a test result using 2 x Samsung 850 Pro. Should you be interested there is also a four drive version.
I don't have experience with ...
SATA 1 150mb/s
SATA 2 300mb/s
SATA 3 600mb/s
If the RAID controller has SATA 3 connectors it should be able to handle it. If you are looking for raw speed a samsung ssd will do 500-550mb/s read and 300+mb/s write beating any 2 hard drives you can attach via SATA.
You might look for a 2-Bay USB HDD case, for example the LOGILINK UA0154A.
There are plenty of casings around, see Google Shopping, but this depends on the size of your disks (2,5"; 3,5", ...). I would recommend two 2,5" SATA SSD's to get the best performance.
Edit: I really recommend to plug both drives to the same controller (let the "external hardware" ...
In general, performance RAID and SSD are not a thing you need to do. The performance improvement is pretty minimal, and you'd only want to use RAID as a way to maintain multiple drives in case one begins to fail, allowing the other drives in the cluster to handle the load. If you're talking 10+ drives, performance RAID can come back into play.
HDD simply ...
The drives will be purchased separately from the NAS.
I suggest your better off building a PC.
Use a NAS with four bays, two for large HDD, and two for fast SSD
Case with 3 5.25 bays are easy to come by. I have a SSD enclosure that fits into a 5.25 bay that holds 4 SSD. Also using 2x 5.25 bays you can easily have room for 2 or even 3 regular hdd.
I tend to splurge a bit on NAS type components (Drobo, Icy Box) so I can't make a personal recommendation when it comes to the cheaper end of the scale, but I can make a general recommendation when it comes to buying the drives you are going to populate your chosen NAS with: don't buy them from the same place.
Do buy the same model, from the same ...