Difference between revisions of "Live migration"
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| − | The <code> | + | The <code>criu</code> utility can be used to perform live migration of apps or containers. This page is a sort of HOWTO describing this. |
== Migration sequence == | == Migration sequence == | ||
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=== Dump === | === Dump === | ||
| − | Take tasks you're about to migrate and dump them into some place, asking <code> | + | Take tasks you're about to migrate and dump them into some place, asking <code>criu</code> to leave them in stopped state after dump: |
| − | [src]# | + | [src]# criu dump --tree <pid> --images-dir <path-to-existing-directory> --leave-stopped |
The directory you put images to can reside on the shared file-system if you're using one. In this case you can skip the Copy step and proceed to Restore. | The directory you put images to can reside on the shared file-system if you're using one. In this case you can skip the Copy step and proceed to Restore. | ||
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Go to the destination node and restore the apps from images on it: | Go to the destination node and restore the apps from images on it: | ||
| − | [dst]# | + | [dst]# criu restore --tree <pid> --images-dir <path-to-images> |
=== Kill === | === Kill === | ||
Revision as of 16:40, 30 April 2013
The criu utility can be used to perform live migration of apps or containers. This page is a sort of HOWTO describing this.
Migration sequence
In order to live-migrate an application or a container you should make sure, that files, that are/can be accessed by processes you're migrating are available on both nodes -- source and destination. This can be achieved by using either shared file-system such as NFS, GlusterFS or CEPH, or by using rsync to copy files from one box to another. Further in this article we assume, that the file-system is the same on both sides.
In order to live migrate tasks you should do these steps:
Dump
Take tasks you're about to migrate and dump them into some place, asking criu to leave them in stopped state after dump:
[src]# criu dump --tree <pid> --images-dir <path-to-existing-directory> --leave-stopped
The directory you put images to can reside on the shared file-system if you're using one. In this case you can skip the Copy step and proceed to Restore.
Copy
Copy images to destination node:
[src]# scp -r <path-to-images-dir> <dst>:/<path-to-images>
Restore
Go to the destination node and restore the apps from images on it:
[dst]# criu restore --tree <pid> --images-dir <path-to-images>
Kill
If everything went OK you can return on the source node and kill stopped tasks on it.
[src]# FIXME put command here
Notes
The directories with images would contain two copies of applications memory, which may be space-consuming. The CRIU can perform disk-less migration to address this.