Dave Howorth wrote:
Philipp Thomas wrote:
* Linda Walsh (suse@tlinx.org) [20120823 03:26]:
Oh -- you meant linux-based sw-raid. SW-raids are included in many Dell BIOS's, no-hardware is involved -- just SW -- and they work fine to boot off of. That's what is normally called fakeRAID as the BIOS only sets up the RAID drives and everything else is done by software. And it *only* works reliably with Grub when doing RAID1 i.e. mirroring. Grub can't boot reliably from striping sw-raids as it has no driver for that.
Holy poop, you are kidding? Lilo has no special support for booting from them either -- it sees them as 1 single SDA1 device as presented by the BIOS. Windows boots from them fine as well... I find it hard to believe grub woudln't. It looks like 1 HD to the OS -- Vs. on my HW based RAID that's also booted from the ROM (different sys), the OS (linux) CAN tell there are underlying disks after it boots up. I'd love to talk about what crap GRUB is for not being able to boot on something so common, but I'm 90% certain it does. It IS a type of LSI based RAID -- just no HW support, but i'd guess LSI put in enough HW to at least fool an OS to make it look like 1 disk -- only supports RAID0,1 or 0+1 (or is that 1+0?)... But it's their default disk device if you don't buy a raid card.
Just for clarity, there are two different RAID implementations to consider here.
"linux-based sw-raid" would normally be taken to mean RAID implemented by linux and using the mdadm program and friends, with device names like /dev/md*.
BIOS-based fakeraid is different.
--- Nothing fake about it for what it does. It interleaves 4 150MB/s SAS drives to yield up to 600MB/s just fine -- it doesn't do RAID5 or 6 like HW RAID cards do, but for RAID1/RAID0, SW can do that fairly easily and efficiently. I'm more likely to think of SW RAID5 as 'fakeraid', given it's performance, but that's just some sorta 'put-down' or 'one-upmanship that I wouldn't even think of if you hadn't used the term. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org