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Re: [alpine-user] alpinelinux 3.3.1 can not boot, when root is on lvm, which is on raid1

From: Dieter Bloms <dieter_at_bloms.de>
Date: Thu, 21 Jan 2016 16:31:54 +0100

Hello Natanael,

On Mon, Jan 11, Natanael Copa wrote:

> On Mon, 11 Jan 2016 08:59:19 +0100
> Natanael Copa <ncopa_at_alpinelinux.org> wrote:
>
> > On Fri, 8 Jan 2016 21:56:34 +0100
> > Dieter Bloms <alpinelinux.org_at_bloms.de> wrote:
> >
> > > Hi,
> > >
> > > I installed alpinelinux 3.3.1 with manual disc mode.
> > > My root is a logical volume in a volume group on a raid1 system.
> > > During boot the raid is activated, but the logical volumes are not.
> > > So I have to activate it manually and mount it to /sysroot.
> > > After that I can boot into alpinelinux.
> > >
> > > Is it a known problem, that lvm on a raid is not activated in the
> > > initramfs during boot ?
> >
> > It is a known problem. I have the same on my workstation. Sometimes it
> > works and sometimes it fails so I think it is a timing issue.
> >
> > Today I looked at it a bit and it seems that /sbin/lvm is never
> > executed from initramfs. It means that the nlplug-findfs times out
> > before it gets the hotplug event for mdadm devices.
> >
> > I think we have a few options for fixing it:
> >
> > 1) when mdadm is run, make it wait til all mdadm devices are run before
> > exit. I don't know if this is possible, but nlplug-finds will not
> > exit til all forked children has exited. This means that mdadm
> > executes, initalizes the raid devices, and exits long before the
> > kernel generates the uevent for the raid device. If we could make
> > mdadm not exit til the uevent is generated, then we should be fine.
> > I don't know if there is any option for that. (probably not)
> >
> > 2) When mdadm is started, increase the default nlplug-findfs timeout
> > (250ms) so kernel gets enough time to generate the raid device
> > uevent before nlplug-findfs times out. We could increase it with 1
> > sec for example? The problem is that I don't know what is a good
> > value since it may depend on the hardware. It will also make boot
> > slower when you boot to tmpfs root but does not have any apkovl. I
> > doubt there will ever exist any such setup so the slowdown here is
> > acceptable.
> >
> > 3) When boot option `root=...` is specified, increase the default
> > nlplug-findfs timeout (250ms) to something significantly longer.
> > Maybe 2 seconds? 5 seconds? If we actually timeout, it means that we
> > will failed to find the rootfs and the boot will fail. So it makes
> > sense to increase the timeout for making it not give up that fast.
>
> I tested this. it didnt help. must be mdadm that mdadm delete/recreate
> the /dev/md* device node so that when the uevent trigger happens,
> the /dev/md* device node temporarily does not exist.
>
> I think we might need block event handling while mdadm executes. We do
> the same for cryptsetup.

did you have any success on this topic ?

-- 
Regards
  Dieter
--
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Received on Thu Jan 21 2016 - 16:31:54 GMT