Upgrading
Couchbase Server can be upgraded online (using swap rebalance or the standard online upgrade), offline, or using XDCR.
Install the latest version of Couchbase Server. The installer will automatically detect the files from the earlier installation and convert them to the correct format, if needed.
| Feature | Online Upgrades | Offline Upgrades |
|---|---|---|
| Applications Remain Available | Yes | No |
| Cluster Stays in Operation | Yes | No |
| Cluster must be Shutdown | No | Yes |
| Time Required | Requires Rebalance, Upgrade, Rebalance per Node | All nodes in Cluster Upgraded at Once |
Online upgrades
When you perform an online upgrade, there is no need to take the cluster down and application keeps running during the upgrade process.
- Online upgrade with swap rebalance
- For swap rebalance, first add a node to the cluster and then perform a swap rebalance to
shift data from an old node to the new one. This is a preferred upgrade method when there
is not enough cluster capacity to handle data when an old node is removed. It is also much
faster from the standard online upgrade because you only need to rebalance each upgraded
node once.
To perform an online upgrade with swap rebalance, see Online upgrade with swap rebalance.
- Standard online upgrade
- For standard online upgrade, take down one or two nodes from a
cluster and rebalance so that remaining nodes handle incoming requests. You can use this upgrade option
only if you have enough remaining cluster capacity to handle the nodes you remove and
upgrade. You need to perform rebalance twice for every node you upgrade: first
to move data to remaining nodes, and then to move data to the new nodes.
Standard online upgrades can take a while because each node must be taken out of the cluster, upgraded to a current version, brought back into the cluster, and then rebalanced.
Offline upgrades
Offline upgrades can take less time than online upgrades because all nodes in the cluster can be upgraded at once.
An offline upgrade must be well-planned and scheduled. First, shut down your application so that no more incoming data arrives. Second, verify that the disk write queue is 0 and then shut down each node. This way you know that Couchbase Server has stored all items onto disk during shutdown. After shutting down applications and nodes, perform the upgrade on each machine and then bring the cluster and applications back again.
To perform an offline upgrade, see Offline upgrade process.