CODEWITHSUNDEEP
virtual-machinegoogle-compute-enginecentos6
warren
warren

Reputation: 21

Cannot connect to Compute Engine CentOS Virtual Machine

I am new to Virtual Machines and CLI so please bear with me.

I have a CentOS 6.5 running on Compute Engine.

I ran yum update (without creating a snapshot of the previous disk - Yes I am an idiot) and not I cannot connect to the machine using the ip address.

I tried the following steps.

Tried to connect through Filezilla - didn't work. Tried through Putty - didn't work Tried through the browser option given by the CE console - didn't work. I even tried creating a snapshot and starting up another VM with the snapshot - didn't work.

If anyone knows how I can get the files and folders out from the previous disk, I can start up a new VM and transfer everything again.

I do not have the latest database and this is important.

Please help! Thanks Warren

Upvotes: 0

Views: 144

Answers (2)

Misha Brukman
Misha Brukman

Reputation: 13424

The way to recover is to delete your VM without deleting the disk, then create another VM with its own boot disk, attach and mount the original disk, and recover any data that you need from it.

First things first: on the VM instances page, click on the instance name that is currently running with that disk, and uncheck the box "Delete boot disk when instance is deleted". Then delete the instance.

Now, create a new instance with its own boot disk. To differentiate this new disk from the original boot disk:

  • using a different OS (or version of the OS) for the new disk, e.g., if using Ubuntu, try a different version or use Debian; if using RHEL, try CentOS, or vice versa
  • see which one is mounted at / — this should be the new disk

Mount the original disk as read-only and recover any information you need. Once you have a backup of your data, you can remount it with read-write access and try to fix it (but back up the data first!).

Upvotes: 1

warren
warren

Reputation: 21

I finally solved this problem thanks to Misha for sending me in the right direction.

The steps are below for anyone who has the same issue.

Problem:

While updating the Centos server using yum update, I was unable to connect back to the server. I tried all possible combinations but no luck. This seems to be a known issue as there was some material on the Compute Engine site regarding this.

Solution:

I followed the steps as Misha suggested. I started up another VM with its own boot disk and then attached the original disk with read write access.

Note: I was unable to mount the disk as just read only.

The commands were

mkdir /mnt/sdb1

mount /dev/sdb1 /mnt/sdb1

Once I mounted the VM, I copied the files from the html folder in the sdb1 disk to the html folder in the sda1(the new boot disk).

The database was a bit more challenging.

I tried quite a few times but copying the files from /dev/sdb1/var/lib/mysql into the new disk mysql folder was not working.

I found some tutorials but nothing helped.

Finally I downloaded the files from within the /dev/sdb1/var/lib/mysql and put them in my local windows mysql installation within the data folder.

Remember you have to download everything which includes the ib_logfile0 , ib_logfile1 and ibdata1 including the folder which has the *.frm files.

Then I opened localhost/phpmyadmin and voila... the files were there.

The rest was pretty simple... Exporting and uploading the SQL scripts back to the server.

This took me about 12 hours to figure out.

Thanks again Misha.

Upvotes: 1

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