Question
How to find logs of the container's live migration?
Answer
Starting from Virtuozzo Hybrid Server version 7 Checkpoint and Restore in User Space technology is used for live container migration.
The initial information about migration errors can be gathered from the migration command output. It can be composed incorrectly, or some other obvious error may occur. If it is not clear what caused the issue, check:
1. vzmsrc and vzmdest logs to find out at which stage the migration failed. Run on source node:
# grep vzmsrc /var/log/messages
and on the destination node:
# grep vzmdest /var/log/messages
2. Dump stage issues should be checked on the source node. :
/var/log/phaul.log
/vz/dump/CT_UUID/dmp-*
Restore stage logs are located on the destination node in:
/var/log/phaul-service.log
/vz/dump/CT_UUID/rst-*
Known limitations
1. Containers with any of these items cannot be migrated in live mode:
- External bind mount
- tasks under gdb or strace
- tasks that use sockets other than TCP, UDP, UNIX, packet, and netlink
- Docker containers inside
- Devices passed from the hardware node or virtual devices like GRE tuntap
A full list of limitations can be found here.
2. CRIU version on the destination node should not be older than on the source node. As a best practices recommendation, ensure that CRIU packages are updated on both nodes.
To check the CRIU version:
# rpm -qa | grep criu
To update the system:
# yum update