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Created page with "Please, read the article about Live migration before this one. This page describes how to reduce the freeze time of an application by using the [[memory changes tracking]..."
Please, read the article about [[Live migration]] before this one.
This page describes how to reduce the freeze time of an application by using the [[memory changes tracking]] ability.
== Migration sequence ==
The steps below look like those in regular live migration, but include one of more pre-dump stages.
=== Pre-dump ===
Take tasks you're about to migrate and pre-dump them into some place. Tasks will remain running after pre-dump, unlike regular dump.
[src]# criu pre-dump --tree <pid> --images-dir <path-to-existing-directory-A>
The directory with images can be on a shared storage, or you can use [[disk-less migration]] to avoid the '''Copy''' step.
=== Dump ===
Now you can do regular dump of your processes.
[src]# criu dump --tree <pid> --images-dir <path-to-existing-directory-B> --prev-images-dir <path-to-directory-A-relative-to-B> --leave-stopped
Note, that
# this dump would work faster, than it would if there were no the pre-dump stage, as this dump only takes the memory that has changed, since the pre-dump step.
# the <code>--prev-images-dir</code> should contain path to the directory with pre-dump images ''relative to the directory where the dump images will be put''
=== 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
[[Category: HOWTO]]
This page describes how to reduce the freeze time of an application by using the [[memory changes tracking]] ability.
== Migration sequence ==
The steps below look like those in regular live migration, but include one of more pre-dump stages.
=== Pre-dump ===
Take tasks you're about to migrate and pre-dump them into some place. Tasks will remain running after pre-dump, unlike regular dump.
[src]# criu pre-dump --tree <pid> --images-dir <path-to-existing-directory-A>
The directory with images can be on a shared storage, or you can use [[disk-less migration]] to avoid the '''Copy''' step.
=== Dump ===
Now you can do regular dump of your processes.
[src]# criu dump --tree <pid> --images-dir <path-to-existing-directory-B> --prev-images-dir <path-to-directory-A-relative-to-B> --leave-stopped
Note, that
# this dump would work faster, than it would if there were no the pre-dump stage, as this dump only takes the memory that has changed, since the pre-dump step.
# the <code>--prev-images-dir</code> should contain path to the directory with pre-dump images ''relative to the directory where the dump images will be put''
=== 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
[[Category: HOWTO]]