Ubuntu
mdadm package

degraded raid boot process should interactively prompt user before dropping to recovery shell

Bug #257568 reported by Dustin Kirkland  on 2008-08-13

Affects		Status	Importance	Assigned to	Milestone
	mdadm (Ubuntu)	Fix Released	Wishlist	Dustin Kirkland 

Bug Description

Binary package hint: mdadm

Opening a bug, based on discussion on the Ubuntu-Server mailing list.

:-Dustin

On Wed, Aug 13, 2008 at 5:59 AM, Matt Zimmerman <email address hidden> wrote:
> On Tue, Aug 12, 2008 at 05:19:32PM -0700, Mathias Gug wrote:
>> ==== Boot Support for Degraded RAID ====
>>
>> kirkland has been working on adding RAID support to grub-install. His patch is
>> waiting for sponsoring. He hopes it will make it for alpha4 scheduled to be
>> released on Thursday. If so mathiaz suggested that this new feature should be
>> documented in the Release Notes in order to get more testing.
>>
>> The last item he's working on is adding a question during the installation on
>> whether the system should be set to boot from a degraded array (defaulting to
>> No, which matches the current behaviour).
>
> It appears from that if this feature is not enabled, the system will fail
> hard to an initramfs shell. Instead, how about giving the user the option
> to continue?
>
> Waiting for root file system...
>
> ** WARNING: The root filesystem was found on a degraded RAID array! **
>
> The system may have suffered a hardware fault, such as a disk drive failure.
> You may attempt to start the system anyway, or stop now and attempt manual
> recovery operations.
>
> If you choose to continue, the system may start normally, but performance
> may be degraded, and a further hardware fault could result in permanent data
> loss.
>
> If you abort now, you will be provided with a recovery shell.
>
> Do you wish to continue? [y/N]
>
> This should present no more risk than dropping to a shell, and gives the
> user the guidance to make an informed decision.
>
> --
> - mdz
>
> --
> ubuntu-server mailing list
> <email address hidden>
> https://lists.ubuntu.com/mailman/listinfo/ubuntu-server
> More info: https://wiki.ubuntu.com/ServerTeam
>

Related branches

lp:~csurbhi/+junk/mdadm.fixes

lp:ubuntu/intrepid/mdadm

lp:~xnox/ubuntu/natty/mdadm/natty-updates

Dustin Kirkland  (kirkland) on 2008-08-13

Changed in mdadm:
assignee:	nobody → kirkland
importance:	Undecided → Wishlist
status:	New → In Progress

Revision history for this message

Dustin Kirkland  (kirkland) wrote on 2008-08-13:

mdadm.257568.debdiff Edit (2.2 KiB, text/plain)

Patch attached.

:-Dustin

Revision history for this message

Jools Wills (jools) wrote on 2008-08-13:

What about machines which the sysadmin has only remote access to ? He will want the machine to boot into degraded mode, so services can be running until he can contact someone at the data centre to replace a disk. having it stop at a prompt in this scenario is not helpful.

Revision history for this message

Matt Zimmerman (mdz) wrote on 2008-08-13: Re: [Bug 257568] Re: degraded raid boot process should interactively prompt user before dropping to recovery shell

On Wed, Aug 13, 2008 at 12:54:53PM -0000, Jools Smyth wrote:
> What about machines which the sysadmin has only remote access to ? He
> will want the machine to boot into degraded mode, so services can be
> running until he can contact someone at the data centre to replace a
> disk. having it stop at a prompt in this scenario is not helpful.

That is a separate issue; there is already a configuration option and this
bug is only about what to do when the option is turned off.

--
- mdz

Revision history for this message

Dustin Kirkland  (kirkland) wrote on 2008-08-13: Re: [Bug 257568] Re: degraded raid boot process should interactively prompt user before dropping to recovery shell

On Wed, Aug 13, 2008 at 7:54 AM, Jools Smyth <email address hidden> wrote:
> What about machines which the sysadmin has only remote access to ? He
> will want the machine to boot into degraded mode, so services can be
> running until he can contact someone at the data centre to replace a
> disk. having it stop at a prompt in this scenario is not helpful.

It will NOT stop at this prompt if either:

* The user has BOOT_DEGRADED=true in /etc/initramfs-tools/conf.d/mdadm, or
* The user passes "bootdegraded=true" on the kernel boot parameter

It will only stop at this prompt just before dropping to a busybox
recovery shell in the initramfs, which is also only useful if you're
standing in front of the console.

:-Dustin

Revision history for this message

Jools Wills (jools) wrote on 2008-08-13:

Aaah ok. then I'm happy ;-)

Revision history for this message

Dustin Kirkland  (kirkland) wrote on 2008-08-13:

I have looked into providing a timeout for this prompt, however the extraordinarily limited ash shell in busybox makes this very difficult.

Something like this seems to work well in bash/dash/ash, however, it does not work properly in busybox.

                        # Set a 15-second timeout for this question
                        trap : USR1
                        (sleep 15 && kill -USR1 "$$" 2>/dev/null) & pid=$!
                        read -p "Do you wish to boot the degraded RAID? [y/N]: " -r BOOT_DEGRADED
                        kill "$pid" 2> /dev/null

In any case, perhaps this is a nice-to-have, but does not have to be part of this commit.

I've tested the above debdiff and I'm satisfied with it. Requesting sponsorship.

:-Dustin

Revision history for this message

Dustin Kirkland  (kirkland) wrote on 2008-08-14:

mdadm.257568.debdiff Edit (2.3 KiB, text/plain)

Turns out "read" will take a "-t" option, but it cannot take place after the "-r" option.

Updated patch attached. Tested, requesting sponsorship.

:-Dustin

Revision history for this message

Dustin Kirkland  (kirkland) wrote on 2008-08-14:

Screenshot.png Edit (18.7 KiB, image/png)

Screen shot of the testing, for good measure ;-)

:-Dustin

Revision history for this message

Launchpad Janitor (janitor) wrote on 2008-08-14:

This bug was fixed in the package mdadm - 2.6.7-3ubuntu3

---------------
mdadm (2.6.7-3ubuntu3) intrepid; urgency=low

  * debian/initramfs/init-premount: provide a safety net, interactive prompt
    on boot before dropping to busybox shell if the RAID is degraded; prompt
    times out after 15 seconds, (LP: #257568).

-- Dustin Kirkland <email address hidden> Wed, 13 Aug 2008 14:02:29 -0500