NetApp makes some nice hardware that you can occasionally find for a low price on eBay. Unfortunately, it is typically hard to reuse since NetApp tends to require specific firmware on the hard drives in their drive shelves. So you are then locked into their harder to find and higher-priced drives.
With a bit of experimenting, I found a method to get around this for at least one family of hardware.
Netapp’s DS4243 is a 24-bay SAS 6Gbps drive shelf. It typically is configured with a pair of supplies (can support up to 4) and two IOM3 modules (which only support 3Gbps, but other versions exist). I managed to pick one of these up off eBay for just under $100 with the pair of supplies and IOM3 modules mentioned.
Note I didn’t even try to use the IOM3 modules. There might be other ways around the limitations I read about online, but I found a simple and inexpensive option that allows the disk shelf to be used as a generic JBOD array.
I also had a Dell Compellent HB-1235 12-bay SAS 6Gbps drive shelf. This drive shelf comes with a pair of much longer named controllers (HB-SBB2-E601-COMP) that already present the drive shelf as a JBOD array to FreeNAS. It turns out, these were manufactured by a company called Xyratex, who just happens to also manufacture the Netapp DS4243.
So what would the chance be that a Dell controller would work in the Netapp drive shelf?
I did some research, and the form and fit of the controllers matched perfectly. The connectors are identical and placed in the same locations.
Now there is a chance that the pinout could have changed, power rails could be different, or some other issue might exist due to the fact that these weren’t specified to be connected together, but I was willing to take that chance for the sake of research. Designing hardware in a similar industry, I took a bet that they were at least close enough to do something without blowing up. That only question for me was how well would it work.
So all there was left to do was to plug it in and power it up!
I was curious if possibly the HB-1235 controller would only see half of the NetApp drive shelf, since it was specifically used in a 12-bay drive shelf. I purposely inserted a 500GB drive in bay 24 to test if it would work, and it identified properly with no issues at all.
So they identified, but would there be any stability issues? To at least get a first-order estimate of this, I copied roughly 250GB of data to the array of 6x 3TB drives and had no issues. This was done over a 1Gb link. After the copy was complete, a scrub of the volume was also successful.
The HB-1235 with two modules and two supplies cost me $120, and the NetApp was around $80. Each unit only needs one module to run (though the HB-1235 seems to want to run the power supply fans on high when only one module is inserted). A separate modules runs about $50, so you on a good day on eBay you can have a full 24-bay generic disk shelf for less than $200.