Who Installed the OpenStack Matters, But Here is Somewhat Generalized Guide to Evoke the Rescue Mode on Linux Instance via Python Nova Client. Rackspace, for example runs OpenStack but they have their own web GUI based method to bring the Rescue mode. This guide to OpenStack Nova instance rescue will work for your own OpenStack installation as well as on HP Cloud.
Steps For OpenStack Nova Instance RESCUE (HP Cloud) : Install Python Client Tools
Steps For OpenStack Nova Instance RESCUE (HP Cloud)
nova help rescue
on local computer’s Terminal/iTerm2 window to get command line help :Advertisement
Then you can run
nova list command to get the instance name or ID of the server. The command format will be :
nova rescue serverID
Original instance will loaded into the rescue instance under
/dev/vdb for HP Cloud. Before you access the information you will need to mount
sudo mkdir /example/
sudo mount /dev/vdb1 /example
Before mounting, you possibly want to run the
fdisk -l command. You will get a thing like this :
Disk /dev/vdb1: 2147 MB
This is the rescue mode filesystem. Other one will be bigger in GB – that is the server’s file system. We can now access the files through the
/example directory. Just remember that you will need to put “/example” or what you will use as name in front of the usual paths to get to the files. For example, if you have a problem in the
/etc/hosts file, you will actually access that file at:
If you chowned the file wrongly from root, then root will be at
/example/. It s honestly not possible to predict what error you did and what steps you should do to undo.
You can get rid off rescue mode by this command from local host :
nova unrescue serverID
It is always better to take a snapshot before any work. If simple
apt-get upgrade breaks the system, it is very difficult to roll back or undo without snapshot.