The test-cases performed with the patch:
Install the modified multipath-tools' binary packages; the initramfs is
updated with the changes.
Reboot. The system booted successfully; good.
Notice:
- unmodified kernel cmdline
- root filesystem mounted from the 'by-uuid/multipath-<UUID>' symlink
- it points to a device-mapper virtual block device
- the symlink is unique (no other devices claim it).
$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinux-3.19.0-9-generic
root=UUID=7fec6766-3166-4395-982a-555ecce92667 ro
$ df /
Filesystem
1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
31483800 2374984 27486444 8% /
$ udevadm info -q path
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
/devices/virtual/block/dm-4
$ ls -1
/run/udev/links/*by-uuid*multipath-7fec6766-3166-4395-982a-555ecce92667
b252:4
Verify the failure hook.
Reboot with 'break=top,post-multipath'.
Reduce the wait-for-root timeout for debugging purposes.
(initramfs) sed 's:\(ARCHDELAY\)=[0-9]\+:\1=10:' -i /scripts/local
(initramfs) exit
Check the expected root device:
(initramfs) cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinux-3.19.0-9-generic
root=UUID=7fec6766-3166-4395-982a-555ecce92667 ro break=top,post-multipath
Initially, things are alright:
(initramfs) ls -l
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
lrwxrwxrwx 1 10
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667 -> ../../dm-3
Now, make things wrong:
(initramfs) multipath -F
(initramfs) ls -l
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
ls: /dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667:
No such file or directory
(initramfs) exit
~10 seconds for wait-for-root timeout...
The informative message is displayed; good; the failure hook is OK.
...
WARNING: the root device is supposed to be a multipath device,
but it doesn't look like one: it doesn't have a multipath-UUID
symlink, but it does have a non-multipath (normal) UUID symlink.
...
If you don't try to fix anything and exit, the good and old 'root
device not found' message appears, normally.
...
Gave up waiting for root device. Common problems:
...
ALERT!
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667 does not
exist. Dropping to a shell!
....
Verify the failure hook again, but now let's fix things:
(repeat steps above)
...
WARNING: the root device is supposed to be a multipath device,
but it doesn't look like one: it doesn't have a multipath-UUID
symlink, but it does have a non-multipath (normal) UUID symlink.
...
(initramfs) multipath -v0
(initramfs) exit
The initramfs continued on, and the system booted successfully:
$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinux-3.19.0-9-generic
root=UUID=7fec6766-3166-4395-982a-555ecce92667 ro break=top,post-multipath
$ df /
Filesystem
1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
31483800 2375308 27486120 8% /
$ udevadm info -q path
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
/devices/virtual/block/dm-6
Finally, verify the failure hook again, using the 'TIP (not recommended)' steps.
It boots from the fake symlink (points to underlying/single-path device), so
you get the usual errors about device-mapper failing to get the underlying
because it's locked (root filesystem mountpoint), plus some "waiting" delays.
(repeat steps above)
...
WARNING: the root device is supposed to be a multipath device,
but it doesn't look like one: it doesn't have a multipath-UUID
symlink, but it does have a non-multipath (normal) UUID symlink.
...
(initramfs) uuid=7fec6766-3166-4395-982a-555ecce92667
(initramfs) ln -s $uuid /dev/disk/by-uuid/multipath-$uuid && exit
...
Starting LSB: multipath daemon...
[...] device-mapper: table: 252:4: multipath: error getting device
[...] device-mapper: table: 252:4: multipath: error getting device
...
A start job is running for dev-mapp...x2dpart3.device (37s / 1min 30s)
...
$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinux-3.19.0-9-generic
root=UUID=7fec6766-3166-4395-982a-555ecce92667 ro break=top,post-multipath
$ df /
Filesystem
1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
31483800 2386948 27474480 8% /
$ udevadm info -q path
/dev/disk/by-uuid/multipath-7fec6766-3166-4395-982a-555ecce92667
/devices/vio/71000002/host0/target0:0:1/0:0:1:0/block/sdb/sdb2
$ ls -1
/run/udev/links/*by-uuid*multipath-7fec6766-3166-4395-982a-555ecce92667
ls: cannot access
/run/udev/links/*by-uuid*multipath-7fec6766-3166-4395-982a-555ecce92667: No
such file or directory
(i.e., the fake symlink is expectedly not maintained by
udev, which is part of why this is not recommended :)
If you remove the UUID option from GRUB, it doesn't touch anything:
# GRUB_DISABLE_LINUX_UUID=true update-grub
...
# grep root= /boot/grub/grub.cfg
linux /boot/vmlinux-3.19.0-9-generic
root=/dev/mapper/mpath1-part2 ro
linux /boot/vmlinux-3.19.0-9-generic
root=/dev/mapper/mpath1-part2 ro
linux /boot/vmlinux-3.19.0-9-generic
root=/dev/mapper/mpath1-part2 ro recovery nomodeset
...
# reboot
...
$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinux-3.19.0-9-generic root=/dev/mapper/mpath1-part2
ro
$ df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/mpath1-part2 31483800 2387108 27474320 8% /
So, I believe these tests cover all the functionality added.
Good to go?
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https://bugs.launchpad.net/bugs/1429327
Title:
ISST-LTE: system drops to initramfs after install on multipath disk
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