Bug#678693: Please add a /usr/share/initramfs-tools/scripts/local-block/ script

[Ritesh Raj Sarraf]

On Tuesday 26 June 2012 02:26 PM, Goswin von Brederlow wrote:
>>     One of the problems in current initramfs-tools is with devices that take
>> >     a long time to be detected. My experience with external enclosures was
>> >     that detecting the drives takes rather long, just like USB takes it
>> >     time.
>> >
>> >
>> > Yes. The remote SAN devices have timing issues. And we try best to handle that
>> > situation. I still think that is not the use case you have.
>> > And if you have issues with a remote SAN device setup, please do report it.
>> > Â 
> That is exactly the issue the patch addresses. In your multipath
> local-top script you have:
>
> verbose && log_begin_msg "Loading multipath modules"
> for module in ${MP_MODULES}; do
>   if modprobe "$module"; then
>     verbose && log_success_msg "loaded module ${module}."
>   else
>     log_failure_msg "failed to load module ${module}."
>   fi
> done
> verbose && log_end_msg
>
> verbose && log_begin_msg "Discovering multipaths"
> /sbin/multipath -v $VERBOSITY
> verbose && log_end_msg
>
> if [ -x /sbin/kpartx -a -x /sbin/dmsetup ]; then
>     /sbin/dmsetup ls --target multipath --exec "/sbin/kpartx -a -p -part" >/dev/null
> fi
>
>
> Where do you handle the situation that a device takes longer to apear?
> By the time that script runs the remote device might not yet have
> appeared and then multipath can't setup its part.
>
> Note that the problem isn't the multipath devices not appearing on time
> but the underlying devices you want to multipath taking too long. There
> is nothing multipath can do to make them appear, their detection is
> generally asynchronous.
>
> As an example we have some external raid enclosures here that take over
> 3 minutes to boot. So after a power loss the servers always boot without
> the enclosures and minutes later they show up all of a sudden and only
> then can configure their multipath. Luckily we boot from local disks so
> that isn't as big a problem.
>
> If we had to boot from multipath then we would need to set
> rootdelay=200, causing every boot to just wait for 3 minutes, even on
> warm reboots where that is totaly unnecessary. The initramfs patch I
> made allows to wait until the devices appear. If that happens in 1s then
> the boot continues after 1s.
>
In initrd, yes, we might not be waiting.

I did not see any patch in the bug report. Can you share it?

-- 
Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."


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