Very rough storage validation matrix draft

[Adam Williamson]

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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