Do not create a new volume when creating a new instance from horizon

asked 2019-08-08 03:18:04 -0500

esbdd gravatar image

I create a new instance called "test", and do not create a new volume. I can get access from the console, and can not access from Xshell. As we all know, a volume is used for storing permanently, but the instance do not have a volume. I created a folder called 'new-folder' at /root, and then reboot the instance. After booting successfully, surprisingly, I can see the 'new-folder'. It seems like contradiction. Can you explain for me? Thanks for your attention.

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I don't see a contradiction here. I might misunderstand your question, but if you create a folder in the instance's file system it will be present after reboot. Could it be that you misinterpret the terms ephemeral and persistent disk? During the lifetime of an instance all data will be there.

eblock gravatar imageeblock ( 2019-08-09 05:12:01 -0500 )edit

The difference between ephemeral and persistent disk is what happens if you delete the instance itself. With an ephemeral disk everything will be gone after you delete the VM. With a cinder volume you can delete the VM but keep the volume, e.g. to attach it to a different VM and access the data.

eblock gravatar imageeblock ( 2019-08-09 05:14:30 -0500 )edit

You can also configure that the instance's volume will be deleted, too, if you delete the VM. But the default is to keep volumes after instance deletion. Does this clear things up?

eblock gravatar imageeblock ( 2019-08-09 05:16:10 -0500 )edit