google compute engine mounting persistant disk issues

Question

I am following this guide https://developers.google.com/compute/docs/troubleshooting#ssherrors specifically the section about recovering your persistent disk with another vm.

I am trying to follow this part:

mount /dev/disk/by-id/scsi-0Google_PersistentDisk_myinstance-debugging /mnt/myinstance

This is the error I get:

root@debugger:~# mount /dev/disk/by-id/scsi-0Google_PersistentDisk_marty-wll-debugging /mnt/marty-wll
mount: you must specify the filesystem type

I am unsure of the filesystem due to google-compute disks being used, and the system has already been deleted and attached to another machine following the google developers guide I referenced above.

parted scsi-0Google_PersistentDisk_marty-wll-debugging -l

root@debugger:/dev/disk/by-id# parted scsi-0Google_PersistentDisk_marty-wll-debugging -l
Model: Google PersistentDisk (scsi)
Disk /dev/sda: 10.7GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  10.7GB  10.7GB  primary  ext4


Model: Google PersistentDisk (scsi)
Disk /dev/sdb: 10.7GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  10.7GB  10.7GB  primary  ext4

gave me the information that its "ext4".

although when I issue the following command I still get an error:

root@debugger:~# mount -t ext4 /dev/disk/by-id/scsi-0Google_PersistentDisk_marty-wll-debugging /mnt/marty-wll 
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

dmesg of syslog said :

[ 2452.205447] EXT4-fs (sdb): VFS: Can't find ext4 filesystem

any ideas?

Brian Dorsey Brian Dorsey · Accepted Answer · 2014-02-12T19:42:40

Thanks for pointing this out, I will update the docs. Try adding -part1 to the end of your device name. This will mount the partition, instead of the disk. For your specific case:

mount /dev/disk/by-id/scsi-0Google_PersistentDisk_myinstance-debugging-part1 /mnt/myinstance

Also, there are cleaner aliases, so this should work as well:

mount /dev/disk/by-id/google-myinstance-debugging-part1 /mnt/myinstance

google compute engine mounting persistant disk issues

1 Answers