Chroot environment in a Linux Rescue VM
This article describes how to troubleshoot the chroot environment in the Rescue virtual machine (VM) in Linux.
Ubuntu 16.x && Ubuntu 18.x && Ubuntu 20.04
Stop or de-allocate the affected VM.
Create a rescue VM of the same generation, same OS version, in same resource group and location using managed disk.
Use the Azure portal to take a snapshot of the affected virtual machine's OS disk.
Create a disk out of the snapshot of the OS disk, and attach it to the Rescue VM.
Once the disk has been created, Troubleshoot the chroot environment in the Rescue VM.
Access your VM as the root user using the following command:
sudo su -Find the disk using
dmesg(the method you use to discover your new disk may vary). The following example uses dmesg to filter on SCSI disks:dmesg | grep SCSIYour output will be similar to the following example. In this example, we want the sdc disk:
[ 0.294784] SCSI subsystem initialized [ 0.573458] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252) [ 7.110271] sd 2:0:0:0: [sda] Attached SCSI disk [ 8.079653] sd 3:0:1:0: [sdb] Attached SCSI disk [ 1828.162306] sd 5:0:0:0: [sdc] Attached SCSI diskUse the following commands to access the chroot environment:
mkdir /rescue mount /dev/sdc1 /rescue mount /dev/sdc15 /rescue/boot/efi mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/run chroot /rescueTroubleshoot the chroot environment.
Use the following commands to exit the chroot environment:
exit umount /rescue/proc/ umount /rescue/sys/ umount /rescue/dev/pts umount /rescue/dev/ umount /rescue/run cd / umount /rescue/boot/efi umount /rescueNote
If you receive the error
unable to unmount /rescue, add -l option to the umount command.Example:
umount -l /rescue
Detach the disk from the rescue VM and perform a disk swap with the original VM.
Start the original VM and check its connectivity.
RHEL/Centos/Oracle 6.x && Oracle 8.x && RHEL/Centos 7.x with RAW Partitions
Stop or de-allocate the affected VM.
Create a Rescue VM image of the same OS version, in same resource group (RSG) and location using managed disk.
Use the Azure portal to take a snapshot of the affected virtual machine's OS disk.
Create a disk out of the snapshot of the OS disk, and attach it to the Rescue VM.
Once the disk has been created, Troubleshoot the chroot environment in the Rescue VM.
Access your VM as the root user using the following command:
sudo su -Find the disk using
dmesg(the method you use to discover your new disk may vary). The following example uses dmesg to filter on SCSI disks:dmesg | grep SCSIYour output will be similar to the following example. In this example, we want the sdc disk:
[ 0.294784] SCSI subsystem initialized [ 0.573458] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252) [ 7.110271] sd 2:0:0:0: [sda] Attached SCSI disk [ 8.079653] sd 3:0:1:0: [sdb] Attached SCSI disk [ 1828.162306] sd 5:0:0:0: [sdc] Attached SCSI diskUse the following commands to access the chroot environment:
mkdir /rescue mount -o nouuid /dev/sdc2 /rescue mount -o nouuid /dev/sdc1 /rescue/boot/ mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/run chroot /rescueTroubleshoot the chroot environment.
Use the following commands to exit the chroot environment:
exit umount /rescue/proc/ umount /rescue/sys/ umount /rescue/dev/pts umount /rescue/dev/ umount /rescue/run cd / umount /rescue/boot/ umount /rescueNote
If you receive the error
unable to unmount /rescue, add -l option to the umount command.Example:
umount -l /rescue
Detach the disk from the rescue VM and perform a disk swap with the original VM.
Start the original VM and check its connectivity.
RHEL/Centos 7.x & 8.X with LVM
Note
If your original VM includes Logical Volume Manager (LVM) on the OS Disk, create the Rescue VM using the image with Raw Partitions on the OS Disk
Stop or de-allocate the affected VM.
Create a Rescue VM image of the same OS version, in same resource group (RSG) and location using managed disk.
Use the Azure portal to take a snapshot of the affected virtual machine's OS disk.
Create a disk out of the snapshot of the OS disk, and attach it to the Rescue VM.
Once the disk has been created, Troubleshoot the chroot environment in the Rescue VM.
Access your VM as the root user using the following command:
sudo su -Find the disk using
dmesg(the method you use to discover your new disk may vary). The following example uses dmesg to filter on SCSI disks:dmesg | grep SCSIYour output will be similar to the following example. In this example, we want the sdc disk:
[ 0.294784] SCSI subsystem initialized [ 0.573458] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252) [ 7.110271] sd 2:0:0:0: [sda] Attached SCSI disk [ 8.079653] sd 3:0:1:0: [sdb] Attached SCSI disk [ 1828.162306] sd 5:0:0:0: [sdc] Attached SCSI diskUse the following command to activate the logical volume group:
vgscan --mknodes vgchange -ay lvscanUse the
lsblkcommand to retrieve the lvm names:[user@myvm ~]$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 64G 0 disk ├─sda1 8:1 0 500M 0 part /boot ├─sda2 8:2 0 63G 0 part / sdb 8:16 0 4G 0 disk └─sdb1 8:17 0 4G 0 part /mnt/resource sdc 8:0 0 64G 0 disk ├─sdc1 8:1 0 500M 0 part ├─sdc2 8:2 0 63G 0 part ├─sdc3 8:3 0 2M 0 part ├─sdc4 8:4 0 63G 0 part ├─rootvg-tmplv 253:0 0 2G 0 lvm ├─rootvg-usrlv 253:1 0 10G 0 lvm ├─rootvg-optlv 253:2 0 2G 0 lvm ├─rootvg-homelv 253:3 0 1G 0 lvm ├─rootvg-varlv 253:4 0 8G 0 lvm └─rootvg-rootlv 253:5 0 2G 0 lvmUse the following commands to prepare the chroot dir.
mkdir /rescue mount /dev/mapper/rootvg-rootlv /rescue mount /dev/mapper/rootvg-varlv /rescue/var mount /dev/mapper/rootvg-homelv /rescue/home mount /dev/mapper/rootvg-usrlv /rescue/usr mount /dev/mapper/rootvg-tmplv /rescue/tmp mount /dev/mapper/rootvg-optlv /rescue/opt mount /dev/sdc2 /rescue/boot/ mount /dev/sdc1 /rescue/boot/efiThe
/rescue/boot/and/rescue/boot/efipartitions may not always be located on/dev/sdc2or/dev/sdc1. If you encounter an error while trying to mount these partitions, check the/rescue/etc/fstabfile to determine the correct devices for the/bootand/boot/efipartitions from the broken OS disk. Then, run theblkidcommand and compare the UUID from the/rescue/etc/fstabfile with the output ofblkidto determine the correct device for mounting the/rescue/boot/and/rescue/boot/efiin the repair VM.The
mount /dev/mapper/rootvg-optlv /rescue/optcommand may fail if the rootvg-optlv volume group is absent. If that's the case, you can bypass this command.Access the chroot environment:
mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/run chroot /rescueTroubleshoot the chroot environment.
Use the following commands to exit the chroot environment:
exit umount /rescue/proc/ umount /rescue/sys/ umount /rescue/dev/pts umount /rescue/dev/ umount /rescue/run cd / umount /rescue/boot/efi umount /rescue/boot umount /rescue/home umount /rescue/var umount /rescue/usr umount /rescue/tmp umount /rescue/opt umount /rescueNote
If you receive the error
unable to unmount /rescue, add -l option to the umount command.Example:
umount -l /rescue
Detach the disk from the rescue VM and perform a disk swap with the original VM.
Start the original VM and check its connectivity.
Using the same LVM image
Note
It is possible that you need to deploy the rescue VM using the same lvm image, if that's the case you would need to get around that by modifying some aspects of the rescue VM LVM.
Check the status of the disks prior attaching the disk you want to rescue.
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 /boot/efi ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─rootvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─rootvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─rootvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─rootvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─rootvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─rootvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 / sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 /mntAttach the disk you want to rescue as a data drive
Check the disks again. Note that it will not show you the lvm structures right away.
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 /boot/efi ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─rootvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─rootvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─rootvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─rootvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─rootvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─rootvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 / sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 /mnt sdc ├─sdc1 vfat 93DA-8C20 ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d ├─sdc3 └─sdc4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pUlvm commands will complain about duplicated PV.
# pvs WARNING: Not using lvmetad because duplicate PVs were found. WARNING: Use multipath or vgimportclone to resolve duplicate PVs? WARNING: After duplicates are resolved, run "pvscan --cache" to enable lvmetad. WARNING: Not using device /dev/sdc4 for PV pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU. WARNING: PV pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU prefers device /dev/sda4 because device is used by LV. PV VG Fmt Attr PSize PFree /dev/sda4 rootvg lvm2 a-- <63.02g <38.02gUse the vmimportclone command to import the rootvg from the data drive using another name.
This will also change the UUID of the PV and will activate it.
# vgimportclone -n rescuemevg /dev/sdc4 WARNING: Not using device /dev/sdc4 for PV pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU. WARNING: PV pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU prefers device /dev/sda4 because device is used by LV. # vgchange -a y rescuemevg 6 logical volume(s) in volume group "rescuemevg" now activeVerify the name change
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 /boot/efi ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─rootvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─rootvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─rootvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─rootvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─rootvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─rootvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 / sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 /mnt sdc ├─sdc1 vfat 93DA-8C20 ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d ├─sdc3 └─sdc4 LVM2_member BbZsAT-5oOK-nITn-bHFW-IVyS-y0O3-93oDes ├─rescuemevg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 ├─rescuemevg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d ├─rescuemevg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 ├─rescuemevg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 ├─rescuemevg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 └─rescuemevg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809Rename the rootvg of the rescue VM
# vgrename rootvg oldvg Volume group "rootvg" successfully renamed to "oldvg"Check the disks
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 /boot/efi ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─oldvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─oldvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─oldvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─oldvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─oldvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─oldvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 / sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 /mnt sdc ├─sdc1 vfat 93DA-8C20 ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d ├─sdc3 └─sdc4 LVM2_member BbZsAT-5oOK-nITn-bHFW-IVyS-y0O3-93oDes ├─rescuemevg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 ├─rescuemevg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d ├─rescuemevg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 ├─rescuemevg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 ├─rescuemevg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 └─rescuemevg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809Mount the FS coming from the data drive.
When using xfs, specify the
-o nouuidoption to avoid conflicts with the UUIDs and mount the needed filesystems to perform a chroot:mkdir /rescue mount -o nouuid /dev/mapper/rescuemevg-rootlv /rescue mount -o nouuid /dev/mapper/rescuemevg-homelv /rescue/home mount -o nouuid /dev/mapper/rescuemevg-optlv /rescue/opt mount -o nouuid /dev/mapper/rescuemevg-tmplv /rescue/tmp mount -o nouuid /dev/mapper/rescuemevg-usrlv /rescue/usr mount -o nouuid /dev/mapper/rescuemevg-varlv /rescue/var mount -o nouuid /dev/sdc2 /rescue/boot mount /dev/sdc1 /rescue/boot/efi mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/runThe
/rescue/boot/and/rescue/boot/efipartitions may not always be located on/dev/sdc2or/dev/sdc1. If you encounter an error while trying to mount these partitions, check the/rescue/etc/fstabfile to determine the correct devices for the/bootand/boot/efipartitions from the broken OS disk. Then, run theblkidcommand and compare the UUID from the/rescue/etc/fstabfile with the output ofblkidto determine the correct device for mounting the/rescue/boot/and/rescue/boot/efiin the repair VM. Duplicate UUIDs may appear in the output. In this scenario, mount the partition that matches the device letter from step 5. In the example of this section, the correct partition you should mount is/dev/sdc'. Thedev/sda` represents the operating system currently in use and should be ignored.Verify the mounts
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 /boot/efi ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─oldvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─oldvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─oldvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─oldvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─oldvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─oldvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 / sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 /mnt sdc ├─sdc1 vfat 93DA-8C20 /rescue/boot/efi ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /rescue/boot ├─sdc3 └─sdc4 LVM2_member BbZsAT-5oOK-nITn-bHFW-IVyS-y0O3-93oDes ├─rescuemevg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /rescue/tmp ├─rescuemevg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /rescue/usr ├─rescuemevg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /rescue/opt ├─rescuemevg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /rescue/home ├─rescuemevg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /rescue/var └─rescuemevg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 /rescueUse chroot
chroot /rescue/Verify tge mounts "inside" the chroot environment.
Notice that now rescuemevg-rootlv is the one mounted on /
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─oldvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 ├─oldvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d ├─oldvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 ├─oldvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 ├─oldvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 └─oldvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 sdc ├─sdc1 vfat 93DA-8C20 /boot/efi ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sdc3 └─sdc4 LVM2_member BbZsAT-5oOK-nITn-bHFW-IVyS-y0O3-93oDes ├─rescuemevg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─rescuemevg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─rescuemevg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─rescuemevg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─rescuemevg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─rescuemevg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 /Rename the VG to keep it consistent.
Renaming the vg will keep you from facing issues when regenerating initrd and booting the disk again on the original VM
# vgrename rescuemevg rootvg Volume group "rescuemevg" successfully renamed to "rootvg"Verify the change
# lsblk -f NAME FSTYPE LABEL UUID MOUNTPOINT sda ├─sda1 vfat 93DA-8C20 ├─sda2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d ├─sda3 └─sda4 LVM2_member pdSI2Q-ZEzV-oT6P-R2JG-ZW3h-cmnf-iRN6pU ├─oldvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 ├─oldvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d ├─oldvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 ├─oldvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 ├─oldvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 └─oldvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 sdb └─sdb1 ext4 e72e7c2c-db27-4a73-a97e-01d63d21ccf8 sdc ├─sdc1 vfat 93DA-8C20 /boot/efi ├─sdc2 xfs d5da486e-fdfe-4ad8-bc01-aa72b91fd47d /boot ├─sdc3 └─sdc4 LVM2_member BbZsAT-5oOK-nITn-bHFW-IVyS-y0O3-93oDes ├─rootvg-tmplv xfs 9098eb05-0176-4997-8132-9152a7bef207 /tmp ├─rootvg-usrlv xfs 2f9ff36c-742d-4914-b463-d4152801b95d /usr ├─rootvg-optlv xfs aeacea8e-3663-4569-af25-c52357f8a0a3 /opt ├─rootvg-homelv xfs a79e43dc-7adc-41b4-b6e1-4e6b033b15c0 /home ├─rootvg-varlv xfs c7cb68e9-7865-4187-b3bd-e9a869779d86 /var └─rootvg-rootlv xfs d8dc4d62-ada5-4952-a0d9-1bce6cb6f809 /Proceed with the required activities to rescue the OS, this may include regenerating initramfs or the grub configuration
Exit the chroot environment
exitUnmount and detach the data disk from the rescue VM and perform a disk swap with the original VM
umount /rescue/run/ umount /rescue/dev/pts/ umount /rescue/dev/ umount /rescue/sys/ umount /rescue/proc umount /rescue/boot/efi umount /rescue/boot umount /rescue/var umount /rescue/usr umount /rescue/tmp umount /rescue/opt umount /rescue/home umount /rescueStart the original VM and verify its functionality
Oracle 7.x
Stop or de-allocate the affected VM.
Create a Rescue VM image of the same OS version, in same resource group (RSG) and location using managed disk.
Use the Azure portal to take a snapshot of the affected virtual machine's OS disk.
Create a disk out of the snapshot of the OS disk, and attach it to the Rescue VM.
Once the disk has been created, Troubleshoot the chroot environment in the Rescue VM.
Access your VM as the root user using the following command:
sudo su -Find the disk using
dmesg(the method you use to discover your new disk may vary). The following example uses dmesg to filter on SCSI disks:dmesg | grep SCSIYour output will be similar to the following example. In this example, we want the sdc disk:
[ 0.294784] SCSI subsystem initialized [ 0.573458] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252) [ 7.110271] sd 2:0:0:0: [sda] Attached SCSI disk [ 8.079653] sd 3:0:1:0: [sdb] Attached SCSI disk [ 1828.162306] sd 5:0:0:0: [sdc] Attached SCSI diskUse the following commands to access the chroot environment:
mkdir /rescue mount -o nouuid /dev/sdc2 /rescue mount -o nouuid /dev/sdc1 /rescue/boot/ mount /dev/sdc15 /rescue/boot/efi mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/run chroot /rescueTroubleshoot the chroot environment.
Use the following commands to exit the chroot environment:
exit umount /rescue/proc/ umount /rescue/sys/ umount /rescue/dev/pts umount /rescue/dev/ umount /rescue/run umount /rescue/boot/efi umount /rescue/boot umount /rescueNote
If you receive the error
unable to unmount /rescue, add -l option to the umount command.Example:
umount -l /rescue
Detach the disk from the rescue VM and perform a disk swap with the original VM.
Start the original VM and check its connectivity.
SUSE-SLES 12 SP4, SUSE-SLES 12 SP4 For SAP && ## SUSE-SLES 15 SP1, SUSE-SLES 15 SP1 For SAP
Stop or de-allocate the affected VM.
Create a Rescue VM image of the same OS version, in same resource group (RSG) and location using managed disk.
Use the Azure portal to take a snapshot of the affected virtual machine's OS disk.
Create a disk out of the snapshot of the OS disk, and attach it to the Rescue VM.
Once the disk has been created, Troubleshoot the chroot environment in the Rescue VM.
Access your VM as the root user using the following command:
sudo su -Find the disk using
dmesg(the method you use to discover your new disk may vary). The following example uses dmesg to filter on SCSI disks:dmesg | grep SCSIYour output will be similar to the following example. In this example, we want the sdc disk:
[ 0.294784] SCSI subsystem initialized [ 0.573458] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252) [ 7.110271] sd 2:0:0:0: [sda] Attached SCSI disk [ 8.079653] sd 3:0:1:0: [sdb] Attached SCSI disk [ 1828.162306] sd 5:0:0:0: [sdc] Attached SCSI diskUse the following commands to access the chroot environment:
mkdir /rescue mount -o nouuid /dev/sdc4 /rescue mount -o nouuid /dev/sdc3 /rescue/boot/ mount /dev/sdc2 /rescue/boot/efi mount -t proc /proc /rescue/proc mount -t sysfs /sys /rescue/sys mount -o bind /dev /rescue/dev mount -o bind /dev/pts /rescue/dev/pts mount -o bind /run /rescue/run chroot /rescueTroubleshoot the chroot environment.
Use the following commands to exit the chroot environment:
exit umount /rescue/proc/ umount /rescue/sys/ umount /rescue/dev/pts umount /rescue/dev/ umount /rescue/run umount /rescue/boot/efi umount /rescue/boot umount /rescueNote
If you receive the error
unable to unmount /rescue, add -l option to the umount command.Example:
umount -l /rescue
Detach the disk from the rescue VM and perform a disk swap with the original VM.
Start the original VM and check its connectivity.
Next Steps
Contact us for help
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