On Sat, 2005-05-21 at 11:22 +0200, Steven Moix - Axianet.ch wrote:
Hello, In some weeks I'm going to reinstall some old RedHat9 based servers with Promise FastTrak TX2000 "semi-hardware" RAID1 controllers. I just tried to install CentOS 4.0 on a computer with a spare card and as usual both HDD attached to the RAID1 controller are seen separately by the installer because the specific driver for the TX2000 wasn't loaded. Nothing new here, it was always like this on every distro as far as I know.
The problem with "FRAID" (Fake/Free RAID -- even the, as you called it, "semi-hardware" ones with DRAM) will always be that there is 3rd party licensed code. And that code will never become GPL or even open sourced in any way because not only does Promise (or HPT, or SilImage for that matter) not own it, but the 3rd party that does would see their sales go to 0 if they didn't keep it under proprietary licensure.
It's the same issue with _any_ "software-driven" hardware product. The code is from the same 2-3 companies that the 1,000s of manufacturers actually license from.
As you have discovered, there is the "clean-room" ataraid.c software RAID logic and the individual hptraid.c, pdcraid,c and silraid.c FRAID interface modules. The idea is that there is this "single" core logic for all FRAID cards in ataraid.c, and then the independent hptraid.c, pdcraid.c and silraid.c for each of the FRAID card vendor's products.
I'm sure it's getting dropped because it's basically impossible to keep up with all the little changes in the interfaces or RAID logic of the various FRAID code as well as specific FRAID card instances.
Furthermore, one change in how Windows XP handles disk geometry -- which has been a major issue I've run into as of post-SP1, SP2 and post-SP2 hot-fixes -- when dual-booting means the interface driver could actually destroy the fake array organization easily. The only way I see to address this is if _everyone_ (Linux, FRAID cards, any other disk organization/modification programs) used the LDM Disk Label (aka "Dynamic Disk") as the "standard," which allows a lot of these details to be stored in the disk label (exact disk geometry, journal of changes, etc...).
Reality: FRAID is always slower than Linux LVM/MD or NT LDM. Other than boot-time Int13h services, it offers nothing.