Multipath Causing Backup Tasks to Fail

Issue

Backup tasks fail with errors like these:

Running: mount -t ext4 -o noatime,user_xattr,acl /dev/sdk1 /mnt/onapp-backup-yolzefqirpdpek
mount: special device /dev/sdk1 does not exist
Fatal: Execution of mount -t ext4 -o noatime,user_xattr,acl /dev/sdk1 /mnt/onapp-backup-yolzefqirpdpek failed

Running: ntfsclone -q -s -O /onapp/backups/i/i/iignblsablnmyt /dev/sdl1 > /tmp/onapp-tmp-ntfsclone-sdl.log 2>&1 || ( cat /tmp/onapp-tmp-ntfsclone-sdl.log; rm -f /tmp/onapp-tmp-ntfsclone-sdl.log; exit 1 )
ntfsclone v2016.2.22 (libntfs-3g)
ERROR(2): Failed to check '/dev/sdl1' mount state: No such file or directory
Fatal: Execution of ntfsclone -q -s -O /onapp/backups/i/i/iignblsablnmyt /dev/sdl1 > /tmp/onapp-tmp-ntfsclone-sdl.log 2>&1 || ( cat /tmp/onapp-tmp-ntfsclone-sdl.log; rm -f /tmp/onapp-tmp-ntfsclone-sdl.log; exit 1 ) failed

Environment

• OnApp version 3.2 or later
• LVM datastore
• Dedicated backup server

Resolution 

Edit /etc/multipath.conf on the backup server by adding the following to the blacklist section:

device { 
 vendor "IET" 
 product "VIRTUAL-DISK" 
}

Example:

# cat /etc/multipath.conf
## Use user friendly names, instead of using WWIDs as names.

defaults {
 user_friendly_names yes
 find_multipaths yes
 #from IBM
 #polling_interval 30
}

blacklist {
 wwid 26353900f02796769
 devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
 devnode "^hd[a-z]"
 devnode "sda"

device {
 vendor "IET" 
 product "VIRTUAL-DISK"
 }
}

 Reload the multipathd service.

service multipathd reload

Cause

This is because multipath is trying to interfere with a temporary iSCSI connection between the HV and backup server.