First part of the solution is the SAS controller with external ports. I linked to one earlier:
https://www.ebay.com/itm/LSI-Logic-...ort-6Gb-s-SAS-HBA-Cable-Included/382527261521
That should be fine.
From that, you will need external SAS cables, one for each drive tower. The card I linked to comes with one cable, but here is the kind of cable you need for the second:
https://www.ebay.com/itm/SFF-8088-M...1200-1220-MD3200-3220-MD3600i-2m/263857193638
Several companies make them and they come in different lengths, shorter the better, that one is two meters, and here is one that is one meter:
https://www.ebay.com/itm/Hitachi-Ex...O-SFF-8088-Cable-SC1-K1BS-3ft-1m/392009494826
The kind of connector is standard, but the retention clip release mechanism varies slightly from one manufacturer to another.
Then, to connect that cable into the drive tower, you will need an external SFF-8088 to internal SFF-8087 adapter like this:
https://www.ebay.com/itm/SilverSton...-Mini-SFF8087-to-SFF8088-adapter/253689280729
This one particular one:
View attachment 25097
Is nice because it can be separated into two parts and you can use one for each of the drive towers. The hard part here is that you need to remove the SATA port multiplier hardware and find a way to mount this instead.
From there, and you will need to do this once for each drive tower, use a SFF-8087 cable, like this:
https://www.ebay.com/itm/0-7M-Internal-Mini-SAS-36-Pin-To-SFF-8087-Cable-Black-E2C2/253321506804
Again, many companies make them, the brand is not important, so if you can find a short cable that you can get faster, it is the kind of connector that matters.
Connect from the inside of that external/internal adapter to this SAS expander:
https://www.ebay.com/itm/Intel-RES2...der-Card-SAS-SATA-PCI-Express-x4/141788425753
The kind of expander matters here, because this one has a four pin Molex power input. I am hopeful that those drive towers have an extra Molex power cord that you can use to power this.
View attachment 25098
Just put some electrical tape over the card edge, circled in red, because it isn't needed for what we are doing but we don't want it to short out on anything. It would be nice if there was a place to mount this, but if there isn't it just needs to not be grounded out on anything.
The 'input' cable coming from the server would go into the port closest to the PCI bracket, which you can remove if needed. The 'output' to the drives will need three of these cables:
https://www.ebay.com/itm/Lot-of-2-M...-Forward-Breakout-Internal-Cable/371681252206
They can be connected to the three ports on the opposite end of the card and will connect to the back of the drive cages in the tower where the SATA cables were connected. I made a kind of price list for the cost of all this:
Code:
LSI Logic SAS9200-16e External Dual Port 6Gb/s SAS HBA {Cable Included} = $ 59.00
Hitachi External Mini SAS 26P SFF-8088 TO SFF-8088 Cable SC1/K1BS 3ft/1m = $ 7.00
SilverStone Technology SA022 Dual Mini SFF8087 to SFF8088 adapter = $ 43.99
Internal Mini SAS 36-Pin To SFF-8087 Cable, 0.7M - $4.78 x 2 = $ 9.56
Intel RES2SV240 24 Port Expander Card - $59.95 x 2 = $119.90
Lot of 2 Mini SAS to 4-SATA Forward Breakout - $12.99 x 3 = $ 38.97
All totaled: $ 278.42
I am sure there are other ways to do it, but this was the most cost effective way I could figure to upgrade both drive towers to SAS. About $140 each.