Another risk of hardware RAID controllers is the manufacturer vanishing
We recently inherited a 16-drive machine with a 3ware hardware RAID controller and now I'm busy trying to put it to work. Our first preference is to ignore the RAID part and just the raw disks, which may or may not work sufficiently well (the omens are uncertain at the moment). If we have to use the 3ware hardware RAID, we'll need the proprietary tools that 3ware supplies. And that has turned out to be a problem.
Once upon a time, 3ware was an independent company that made well regarded (at the time) hardware RAID controllers that were also a popular way to do JBOD IDE and SATA disks. Then it was bought by AMCC, which was bought by LSI, which was bought by Avago (now Broadcom). The 3ware website currently points to an Avago IP address that doesn't respond, and good luck finding links for anything that still works, or rather links that point to official sources for it (lots of people have made copies of this stuff and put them up on their own websites). At one point it looked like I might have to resort to the Wayback Machine in order to get something, although that probably didn't have the actual files we'd need.
(If you're ever in this situation, it turns out that you can dig things out of the Broadcom website with enough work. The downloads you want are in the 'Legacy Products' category, for example through this search link.)
I've been generally down on hardware RAID over the years for various reasons, including performance, ease of management and diagnostics, and the portability of software RAID across random hardware. But I have to admit that until now I hadn't really considered the risk of the maker of your hardware RAID card simply vanishing and taking with it the associated software that you needed to actually manage and monitor the RAID at anything except a very basic level.
(Monitoring is especially important for hardware RAID, where without special software you may not get notified about a failed disk until the second one dies and takes your entire array with it. Or a third one, for people using RAID-6.)
Of course even if the company doesn't vanish, products do get deprecated and software related to them stops being maintained. I'm reasonably hopeful that the 3ware utilities will still run on a modern Linux system, but I'm not entirely confident of it. And if they don't, we don't really have very many options. People who use less popular operating systems may have even bigger problems here (I think current versions of Illumos may have wound up with no support for 3ware, for example).