Re: scrub implies failing drive - smartctl blissfully unaware

[Robert White <rwhite@pobox.com>]

On 11/19/2014 04:25 PM, Duncan wrote:
> Most often, however, it's at resume, not original startup, which is
> understandable as state at resume doesn't match state at suspend/
> hibernate.  The irritating thing, as previously discussed, is when one
> device takes long enough to come back that mdraid or btrfs drops it out,
> generally forcing the reboot I was trying to avoid with the suspend/
> hibernate in the first place, along with a re-add and resync (for mdraid)
> or a scrub (for btrfs raid).

If you want a practical solution you might want to look at 
http://underdog.soruceforge.net (my project, shameless plug). The actual 
user context return isn't in there but I use the project to build 
initramfs images into all my kernels.

[DISCLAIMER: The cryptsetup and LUKS stuff is rock solid but the mdadm 
incremental build stuff is very rough and so lightly untested]

You could easily add a drive preheat code block (spin up and status 
check all drives with pause and repeat function) as a preamble function 
that could/would safely take place before any glance is made towards the 
resume stage.

extemporaneous example::

--- snip ---
cat <<'EOT' >>/opt/underdog/utility/preheat.mod
#!/bin/bash
# ROOT_COMMANDS+=( commands your preheat needs )
UNDERDOG+=( init.d/preheat )
EOT

cat <<'EOT' >>/opt/underdog/prototype/init.d/preheat
#!/bin/bash
function __preamble_preheat() {
whatever logic you need
return 0
}
__preamble_funcs+=( [preheat]=__preamble_preheat )
EOT
--- snip ---

install underdog, paste the above into a shell once. edit 
/opt/underdog/prototype/init.d/preamble to put whatever logic in you need.

Follow the instructions in /opt/underdog/README.txt for making the 
initramfs image or, as I do, build the initramfs into the kernel image.

The preamble will be run in the resultant /init script before the swap 
partitions are submitted for attempted resume.

(The system does support complexity like resuming from a swap partition 
inside an LVM/LV built over a LUKS encrypted media expanse, or just a 
plain laptop with one plain partitioned disk, with zero changes to the 
necessary default config.)

-- Rob.