LazyFS is a tool built on top of CRIU to assist process migration between hosts. LazyFS specifically addresses the issue of file migration: currently you can either have both processes (pre-migration and post migration) refer to the same NFS, or you can transfer all the necessary files from one machine to another before restarting the migrated process. LazyFS chooses to find the middleground and instead requests only the files it needs from the original host at the time of a read or write access by the migrated process.
LazyFS is implemented in Go as a FUSE interface. LazyFS relies on SCP currently to transfer images from the original host to the new (post-migration) host. For migration to run smoothly, it is recommended that you setup SSH keys between the hosts before migration.
Note: You only need to install my version of CRIU and LazyFS on the host you are migrating TO, you may use the standard CRIU and do not need LazyFS at all on the host you are migrating FROM.
Install Go and all dependencies for CRIU.
Clone my custom version of CRIU and continue with installation steps from link above. This version simply has a hook on restoration that checks if a file already exists locally: if it does not, it instead opens /lazyfs/(original filename with '.' replacing '/').
Clone LazyFS and compile the CRIU protobuf scheme into Go. In the root
for this project run protoc --go_out=. protobuf/regfile.proto.
Finally, from the root of this project, run go install.
As mentioned above, you may want to configure your migration machines to have one another's SSH keys so that LazyFS can simply SCP files.
To checkpoint a process, run the following, which will output '.img' files in the current directory:
sudo criu dump -j -t <pid>
To start LazyFS:
sudo /path/to/bin/lazyfs MOUNTPOINT IMGDIR USER@RHOST
mountpoint - for compatibility with CRIU, use /lazyfs (as it expects that location).
imgdir - location of all the '.img' files from CRIU's checkpointing process.
user@rhost - the username and the remote host that you are migrating FROM.
To restore a process, run the following in the directory containing the '.img' files:
sudo criu restore -d -j
