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Description of problem:
Trying to restore a backup of a system booting with multipath + software raid, at the rescue prompt, after starting multipathd or executing "rear recover", the multipath devices are not found.
This is due to mdadm building the array at boot, preventing multipath from grabbing the disks later.
Version-Release number of selected component (if applicable):
rear-2.00
How reproducible:
Always
Steps to Reproduce:
1. Setup a VM with 4 SCSI disks (2 images only to have multipath)
2. Install the system with rootvg on RAID1 on the 2 multipath disks
3. Create a rescue image ("rear mkrescue")
4. Boot the rescue image
5. Run "multipathd" and "multipath -l"
Actual results:
No multipath device listed
Additional info:
The workaround is to delete the md device:
mdadm --stop /dev/mdX
The proposed workaround is not sufficient, because as soon as the disk is touched (e.g. via parted), the MD array will be rebuilt.
The fix (on RHEL at least) is to disable the automatic array creationg udev rule /lib/udev/rules.d/65-md-incremental.rules by creating an empty file /etc/udev/rules.d/65-md-incremental.rules
This can be done by appending "touch etc/udev/rules.d/65-md-incremental.rules" to /usr/share/rear/build/GNU/Linux/110_touch_empty_files.sh:
# cat /usr/share/rear/build/GNU/Linux/110_touch_empty_files.sh
...
touch etc/udev/rules.d/65-md-incremental.rules
popd >&8
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2018:3293
Description of problem: Trying to restore a backup of a system booting with multipath + software raid, at the rescue prompt, after starting multipathd or executing "rear recover", the multipath devices are not found. This is due to mdadm building the array at boot, preventing multipath from grabbing the disks later. Version-Release number of selected component (if applicable): rear-2.00 How reproducible: Always Steps to Reproduce: 1. Setup a VM with 4 SCSI disks (2 images only to have multipath) 2. Install the system with rootvg on RAID1 on the 2 multipath disks 3. Create a rescue image ("rear mkrescue") 4. Boot the rescue image 5. Run "multipathd" and "multipath -l" Actual results: No multipath device listed Additional info: The workaround is to delete the md device: mdadm --stop /dev/mdX