It took me ages to get the SX6000 working - what a crap card, from a totally crap company.
My advice to anyone considering getting a Promise card: don't bother - get a 3ware card. Fully supported in FreeBSD and Linux.
I finally managed to get the SX6000 working under an old version of Turbo Linux as per the promise readme for the TurboLinux drivers, so i could boot from the array. That allowed me to build up Linux From Scratch (
http://www.linuxfromscratch.org/) onto another partition - it's not easy, you have to create a initrd image (using bootbox iirc), and compile the SX6000 source driver (which is easier said than done).
The result seems to be stable - the box was up 130 days (It's used as an NFS server) before a disk failure - the array was beeping, so I shut the machine down, replaced the failed disk, turned it back on, and it rebuilt the array. So not all bad.
If you can get it working it seems to do it's job, but I would far rather have used FreeBSD than Linux.
In FreeBSD the i2o driver generates a load of kernel message errors, and of course installing it to the array during set up is a mission in itself - no pst device files, and no built in support for the pst driver. It just didn't seem safe using the card in FreeBSD. I doubt much has changed in the past 150 odd days its been since I tried it in FreeBSD.
Indeed, I notice there are no new drivers for the card on Promise's website - no new linux drivers since March 2002. It's now April 2003. What a shit company.
I hate promise and I swear I'll never buy another promise card. Unfortunately getting 3ware cards in the UK is exceedingly difficult - looks like I'll just have to buy them from the US.