On Mon, 2006-05-15 at 18:52 +0200, Anders Norrbring wrote:
I was kinda surprised.. I enabled hardware JBOD on an ASUS motherboard, built a volume and fired up Linux... It still saw two separate disks, and not the built volume.. Can this be worked around, or will I be forced to use software md?
99.9% of on-board mainboard ATA is _fake_ RAID (FRAID). Other than 16-bit BIOS Int13h Disk Services for boot, it is implemented in 100% _software_ (in the 32/64-bit driver). Because this RAID logic is licensed from a 3rd party, it is _never_ Open Source / GPL. That's why you need to load a "binary only" driver from the vendor. The 2 workarounds are ... - Legacy: GPL ataraid + hptraid/pdcraid/silraid, and - LVM2: GPL Device Mapper 2 (DM2) The legacy approach is a generic "ataraid" logic core that is paired with vendor-specific interfaces. This is largely unreliable and has always netted me toasted data. ;-> The newer approach is to use enhancements to Device Mapper 2 (DM2) in the Logical Volume Manager 2 (LVM2) that can "read" the proprietary organization of various FRAID cards and leverage enhanced LVM2's built-in spanning, striping, mirroring and, possibly, even parity (depend on the card). As a side benefit, LVM2+DM2 can also read several true hardware RAID volumes. E.g., LVM2+DM2 3Ware RAID-0, 1 and 10 volumes, in case your 3Ware card (and its on-board ASIC+firmware) dies. For more on how "FRAID" differs from _real_, hardware RAID, see my 2004 April column in Sys Admin. There are also some related articles in my Blog on FRAID v. true microcontroller and/or ASIC-driven hardware RAID. -- Bryan J. Smith Professional, technical annoyance mailto:b.j.smith@ieee.org http://thebs413.blogspot.com ----------------------------------------------------------- Americans don't get upset because citizens in some foreign nations can burn the American flag -- Americans get upset because citizens in those same nations can't burn their own