How To Migrate A Virtuozzo 4 VPS Container To Virtuozzo 6

I used to work for a national web host. When the parent company that employed me purchased this web host, all the servers were 8-12 years old, with ancient software systems too. One of my tasks was to migrate all the containers from Virtuozzo 4 into Virtuozzo 7. Through trial and error I figured out a path to migrate to Virtuozzo 6, and realized that Virtuozzo 7 could still run Virtuozzo 6 containers.

This guide will show you how to migrate from Virtuozzo 4 to Virtuozzo 6.

Virtuozzo 4 to Virtuozzo 6 Migration

[root@virtuozzo4 ~]# vzlist | grep $hostname

To safeguard ourselves from oopsying the customer's original container, we will first copy their container to which we will perform the actual migration.

[root@virtuozzo4 ~]# vzmlocal -C 4095064:4095065

We need to convert from the old disk format to the new ploop disk format. We can do this while migrating the container to the new Virtuozzo 6 server. If this is the first of many containers you need to migrate, do a dry-run first.

There are a few things to note:

• We are migrating the copy of the original container, not the original container itself
• --readonly leaves the files intact on the Virtuozzo 4 host after migration, but stops the container on the Virtuozzo 4 host after completing the transfer to the Virtuozzo 6 host.
• --online keeps the container online, does a cut-over, and deletes it from the Virtuozzo 4 server. This is destructive, this is why we migrate the copied container and not the original container
• You can't use --online && --readonly together, error: "1534365354: Can't use --online option with --readonly option"

[root@virtuozzo4 ~]# vzmigrate --remove-area no --nostart --keep-dst --readonly --convert-vzfs --verbose --dry-run root@virtuozzo6 4095065

[root@virtuozzo4 ~]# vzmigrate --remove-area no --nostart --keep-dst --convert-vzfs --verbose --online root@virtuozzo6 4095065

Virtuozzo 6 to Virtuozzo 7/8 Migration

At this time, you can optionally migrate the container to a Virtuozzo 7 host which is still capable of running Virtuozzo 6 containers. ChatGPT says Virtuozzo 8 can also support Virtuozzo 6 containers, but I have not tested this.

[root@virtuozzo6 ~]# pmigrate c 4095065 c root@virtuozzo7

Troubleshooting

You might get the following error when trying to start the container on the Virtuozzo 6 host: vcmmd: failed to activate Container: VE not registered. If you dig into the logs you'll likely find memory allocation entries. Simply ensure the host has adequate memory assigned.

[root@virtuozzo7 ~]# prlctl set 4095065 --memsize 4072M