On Mon, 2014-03-17 at 14:58 -0600, Chris Murphy wrote:
> I can't recall whether I dropped this intentionally or
inadvertently,
> I'll try and check. But, of course, HW raid and BIOS RAID are really
> rather different cases from software RAID.
Mmm, well I'm not sure what the failure vectors are for HW and BIOS
RAID. The hwraid case should just look and behave like an ordinary
single device.
Yeah. The possible failure cases here, really, are 'the driver's bust'
and 'the driver got left out of the initramfs', I think.
I've put it back in for now, but we could probably live without it. It's
kind of a PITA to test. (Though it was much *more* of a PITA before I
figured out one of the SATA cables hooked up to my HW RAID controller
was busted.)
The firmware RAID case starts out the same way at boot time, but
then
becomes a variation of software raid, as it's implemented by mdadm,
the only difference being on-disk metadata format.
Yes. This one can break in quite a few ways, and frequently does. It's
an important one to test.
Actually not all firmware RAID is implemented by mdadm; only Intel
fwraid. Other forms of fwraid are implemented by dmraid (still). They're
less common than they once were, but still around.
Looks like in Rawhide's installer Firmware RAID is listed in
specialized disks, which is different than hardware raid I think.
IIRC, it shows up there but it usually *also* shows up as a 'regular'
disk too, but I'd have to check again. I test it every cycle and then
promptly forget the details.
Anyway, I see why they're tested separately.
Yeah, completely different cases. I don't think hardware RAID has
actually seen a failure since I joined RH, but it's at least possible
that it could - though really just having a single 'hardware RAID'
checkbox on the installation validation test matrix isn't a very
sensible approach to testing it, it's a bit like having a 'Graphics
Card' line in the same matrix. One graphics card works? OK, I guess
we're good! :)
> We certainly need to cover SW RAID in the custom testing,
you're right,
> it's an obvious miss. Not sure of the best way to approach it offhand.
> If you'd like to draft something up that'd be great, or else I'll try
> and do it.
I think any raid layout is a small population of the user base. But I
also think there's broad benefit to resiliently bootable raid1, so it
makes sense for us to care about /boot, rootfs, and /home on raid1,
and hopefully refine it so that one day it'll work better on UEFI than
it does now. And then expand scope as resources permit.
Yeah, straightforward two-disk RAID-0 and RAID-1 are probably the most
obvious places to start.
--
Adam Williamson
Fedora QA Community Monkey
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