Re: Unexpected raid1 behaviour

[Tomasz Pala <gotar@polanet.pl>]

Errata:

On Wed, Dec 20, 2017 at 09:34:48 +0100, Tomasz Pala wrote:

> /dev/sda -> 'not ready'
> /dev/sdb -> 'not ready'
> /dev/sdc -> 'ready', triggers /dev/sda -> 'not ready' and /dev/sdb - still 'not ready'
> /dev/sdc -> kernel says 'ready', triggers /dev/sda - 'ready' and /dev/sdb -> 'ready'

The last line should start with /dev/sdd.

> After such timeout, I'd like to tell the kernel: "no more devices, give
> me all the remaining btrfs volumes in degraded mode if possible". By

Actually "if possible" means both:
- if technically possible (i.e. required data is available, like half of RAID1),
- AND if allowed for specific volume as there might be different policies.

For example - one might allow rootfs to be started in degraded-rw mode in
order for the system to boot up, /home in degraded read-only for the
users to have access to their files and do not mount /srv degraded at all.
The failed mount can be non-critical with 'nofail' fstab flag.

> "give me btrfs vulumes" I mean "mark them as 'ready'" so the udev could
> fire it's rules. And if there would be anything for udev to distinguish
> 'ready' from 'ready-degraded' one could easily compose some notification
> scripting on top of it, including sending e-mail to sysadmin.

-- 
Tomasz Pala <gotar@pld-linux.org>