Comment 0 for bug 1940687

While doing some autoinstall tests on an IBM Z / s390x LPAR with FCP/SCSI strorage using multipath (multipath is mandatory in case of using FCP/SCSI) I ran from time to time int a problem where the system does not come up after the post-install reboot and hangs in busybox with the message:

"Gave up waiting for root file system device. Common problems:"
"- Boot args (cat /proc/cmdline)"
"- Check rootdelay= (did the system wait long enough?)"
"- Missing modules (cat /proc/modules; ls /dev)"
"ALERT! /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB7nJ8lOvIK1"
"SvdIFoSIyDIqQG2QpOSk does not exist. Dropping to a shell!"

"BusyBox v1.30.1 (Ubuntu 1:1.30.1-4ubuntu6.3) built-in shell (ash)"
"Enter 'help' for a list of built-in commands."

"(initramfs) [6n"
"ls -l /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB"
7nJ8lO*
"ls: /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB7nJ8lO*: No su"
"ch file or directory"
"(initramfs) [6n"
"cat /proc/cmdline"
root=/dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB7nJ8lOvIK1Svd
IFoSIyDIqQG2QpOSk

"(initramfs) [6n"
"ls -l /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB"
7nJ8lOvIK1Svd
"ls: /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB7nJ8lOvIK1Svd:"
"No such file or directory"
"(initramfs) [6n"
"ls -l /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB"
7nJ8lOvIK1Svd
"ls: /dev/disk/by-id/dm-uuid-LVM-qf611Cct0k4CFKieysi1dCPG3DMo27GRHB7nJ8lOvIK1Svd:"
"No such file or directory"
"(initramfs) [6n"
"ls -l /dev/disk/by-id/dm-uuid-LVM-*"
"ls: /dev/disk/by-id/dm-uuid-LVM-*: No such file or directory"
"(initramfs) [6n"
"ls -l /dev/disk/by-id/"
"lrwxrwxrwx 1 10 wwn-0x6005076306ffd6b60000000000002602 -> ../../dm-0"
"lrwxrwxrwx 1 10 dm-name-mpatha -> ../../dm-0"
"lrwxrwxrwx 1 10 dm-uuid-mpath-36005076306ffd6b60000000000002602 -> ../"
../dm-0
"lrwxrwxrwx 1 10 scsi-36005076306ffd6b60000000000002602 -> ../../dm-0"
"lrwxrwxrwx 1 10 lvm-pv-uuid-BAnixI-pV6E-ntyb-IdEQ-PwPK-R93a-zflLEP ->"
../../dm-2
"lrwxrwxrwx 1 10 wwn-0x6005076306ffd6b60000000000002602-part2 -> ../../"
dm-2
"lrwxrwxrwx 1 10 dm-uuid-part2-mpath-36005076306ffd6b60000000000002602"
"-> ../../dm-2"
"lrwxrwxrwx 1 10 dm-name-mpatha-part2 -> ../../dm-2"
"lrwxrwxrwx 1 10 scsi-36005076306ffd6b60000000000002602-part2 -> ../../"
dm-2
"lrwxrwxrwx 1 10 wwn-0x6005076306ffd6b60000000000002602-part1 -> ../../"
dm-1
"lrwxrwxrwx 1 10 dm-uuid-part1-mpath-36005076306ffd6b60000000000002602"
"-> ../../dm-1"
"lrwxrwxrwx 1 10 dm-name-mpatha-part1 -> ../../dm-1"
"lrwxrwxrwx 1 10 scsi-36005076306ffd6b60000000000002602-part1 -> ../../"
dm-1
"lrwxrwxrwx 1 9 scsi-SIBM_2107900_75DXP712602 -> ../../sdb"
"lrwxrwxrwx 1 10 scsi-SIBM_2107900_75DXP712602-part2 -> ../../sdb2"
"lrwxrwxrwx 1 10 scsi-SIBM_2107900_75DXP712602-part1 -> ../../sdc1"
"(initramfs) [6n"
dmsetup ls --tree -o nodevice
mpatha-part2
`-mpatha
mpatha-part1
`-mpatha

It happens in about one out of 4 cases:

1) failed with missing
   ALERT! /dev/disk/by-id/dm-uuid-LVM-qf611C...
2) fine
3) fine
4) fine
5) failed with missing
   ALERT! /dev/disk/by-id/dm-uuid-LVM-k4CFKi...
6) fine
7) fine
8) ALERT! /dev/disk/by-id/dm-uuid-LVM-NdJQQ6vcagcQESXKnyUI8fHg8KCfeqQw912SyHTJ00LK
ZEAEHwzpaaoQla3k4NuF does not exist
9) fine
10) /dev/disk/by-id/dm-uuid-LVM-Vnda6LhYVr8Yj4OjePUOhF2fv6lbva7Xg2e2v30TJ28M
1mwq8nW0i5DewX14B1cs

I used the daily 19.1 20.04.3 RC ISO, as referenced in the QA Tracker.