M17xR4 mSATA slot and RAID

I have a three short question towards the M17xR4:

I'm thinking about upgrading my M17xR4 to 2* 1.75TB HDDs and a 256GB mSATA SSD. I don't know, if the mSATA-slot supports SATAIII though. The info I found on dell.com in a 2y old thread was, that it's only SATAII, but I can't believe that, that's why I ask here.

Also, I want to use the 2 1.75TB HDDs in RAID, is there anything special I need to know?

And what did the DELL-technician mean with, that it's possible to use the mSATA as a caching SSD. Is that any sort of special configuration, and would that nowadays, with SSDs being large enough for everything that needs to be accessed fast, even make sense?

Tia for all answers <3 .

 

Yes, mSata port in R4 is only a SATA 2 unfortunately. Cashing SSD means you can use a small SSD to speed up your conventional HDD. If you want the fastest possible option, you would be better off using SSD in your regular SATA (which is SATA 3) port and install OS there and use the other port for SSD/HDD for storage. mSATA port can also be used for faster storage, but it will have a limit of 300MB/s (3GB/s), which is still better than regular HDDs could manage. You could also look into SSHDs, which work in a similar way to caching SSD, but the SSD and HDD part is on the same drive. They are a lot cheaper than SSD, only slightly more expensive than the regular HDDs.