Ubuntu – The initramfs will attempt to resume from /dev/dm-1


I'm setting up a new Ubuntu 18.04 server and have already played through one backup/restore loop. So the entire system has been restored from backup with a fresh RAID and LVM volumes.

Now recently, unattended-upgrades has reported this:

Processing triggers for initramfs-tools (0.130ubuntu3.8) ...
update-initramfs: Generating /boot/initrd.img-4.15.0-66-generic
I: The initramfs will attempt to resume from /dev/dm-1
I: (/dev/mapper/vg0-swap)
I: Set the RESUME variable to override this.

I tried to find out what that actually means but wasn't successful. What is it resuming there? Some process of generating boot files? I know it can take a while do do that. Does it have to do with the RAID? That is long finished with its resync. I don't get it. And what's actually wrong? What does that message want me to do? I'm clueless. If I don't need it, how can I make it go away?

The server did reboot successfully twice after that message so it can't be important. (If that "I" was supposed to mean something like that.)

Here's some commands if that helps:

> lvs
  LV   VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root vg0 -wi-ao---- 400.00g
  swap vg0 -wi-ao----   8.00g

> cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 nvme1n1p2[0] nvme0n1p2[1]
      499449152 blocks super 1.2 [2/2] [UU]
      bitmap: 1/4 pages [4KB], 65536KB chunk

md0 : active raid1 nvme0n1p1[1] nvme1n1p1[0]
      523264 blocks super 1.2 [2/2] [UU]

unused devices: <none>

I can't find a good command to show something about these "dm-0" and "dm-1" devices that are also related to the RAID I guess.

Best Answer

  • It may happen when you install another OS alongside the first one. Means that swap partition has changed UUID and you need to adjust that in fstab.

    To check that run sudo blkid, that gives you actual UUIDs of your swaps, swapon -s will show which one is active, then compare its UUID to the one in /etc/fstab.

    If different, edit/create the file /etc/initramfs-tools/conf.d/resume with RESUME=UUID=<swap UUID from blkid>. THen run update-initramfs -u -k all and if it doesn't complain, you win.