The pvesr
command line tool manages the Proxmox VE storage replication
framework. Storage replication brings redundancy for guests using
local storage and reduces migration time.
It replicates guest volumes to another node so that all data is available without using shared storage. Replication uses snapshots to minimize traffic sent over the network. Therefore, new data is sent only incrementally after the initial full sync. In the case of a node failure, your guest data is still available on the replicated node.
The replication is done automatically in configurable intervals.
The minimum replication interval is one minute, and the maximal interval
once a week. The format used to specify those intervals is a subset of
systemd
calendar events, see
Schedule Format
Section 9.2, “Schedule Format” section:
It is possible to replicate a guest to multiple target nodes, but not twice to the same target node.
Each replications bandwidth can be limited, to avoid overloading a storage or server.
Guests with replication enabled can currently only be migrated offline.
Only changes since the last replication (so-called deltas
) need to be
transferred if the guest is migrated to a node to which it already is
replicated. This reduces the time needed significantly. The replication
direction automatically switches if you migrate a guest to the replication
target node.
For example: VM100 is currently on nodeA
and gets replicated to nodeB
.
You migrate it to nodeB
, so now it gets automatically replicated back from
nodeB
to nodeA
.
If you migrate to a node where the guest is not replicated, the whole disk data must send over. After the migration, the replication job continues to replicate this guest to the configured nodes.
High-Availability is allowed in combination with storage replication, but there may be some data loss between the last synced time and the time a node failed.