11.1.1 How to add EADS servers to a cluster without stopping the cluster (scale-out processing)

This subsection explains how to add EADS servers to a cluster without stopping the cluster (scale-out processing).

To add EADS servers to a cluster without stopping the cluster, the following conditions must be satisfied:

All caches in the cluster are memory caches.
The number of redundant copies of data is 2 or more.

If there are disk caches or two-way caches or the number of redundant copies of data plus the original is 1, stop the cluster and then add EADS servers.

For details about how to add EADS servers after stopping a cluster, see 11.1.2 How to add EADS servers to a cluster after stopping the cluster (using only memory caches) and 11.1.3 How to add EADS servers to a cluster after stopping the cluster (using only disk caches).

Organization of this subsection

(1) Check the data distribution among the ranges
(2) Back up the cluster property files (optional)
(3) Verify that there are no errors in any of the EADS servers in the cluster
(4) Install and set up the EADS servers to be added
(5) Add an EADS server to the cluster
(6) Verify that the added EADS server is participating in the cluster

(1) Check the data distribution among the ranges

Execute the eztool storeusage --replica command to check the distribution of the data among the ranges.

eztool storeusage --replica

Command execution example

[Figure]

Based on the execution results of the eztool storeusage --replica command, determine the ranges within which EADS servers need to be added.

Tip

If keys are distributed evenly among the ranges, you can realize the benefits of scale-out processing over the entire cluster by adding one or more EADS servers to each range.

On the other hand, sufficient benefits might not be obtained over the entire cluster in the following cases:

Keys are distributed evenly among the ranges and no EADS server is added to some of the ranges.
Keys are not distributed evenly among the ranges.

To Page Top

(2) Back up the cluster property files (optional)

Back up the cluster property files, if necessary.

When EADS servers are added to an active cluster, the cluster property files are updated automatically based on the information applicable after the EADS servers have been added.

A backup cluster property file containing the current information is created automatically at the path shown below. If another file with the same name already exists, the backup file is not output.

management-directory/conf/eads_cluster.properties.ebf

If a backup cluster property file already exists, the cluster property file is updated during scale-out processing to reflect the new information after the EADS servers have been added. Be aware that if you edit the cluster property file after scale-out processing has been performed and then execute scale-out processing again, the edited information is lost. If you need a backup copy of such an edited cluster property file, back up that cluster property file manually before you perform scale-out processing.

To Page Top

(3) Verify that there are no errors in any of the EADS servers in the cluster

Execute the eztool status command to verify that none of the EADS servers in the cluster is in isolated status (isolated) or stopped status (-----------).

eztool status

Command execution example

[Figure]

If there are isolated or stopped EADS servers in the cluster, restore them.

For details about the restoration procedure, see 12.2.1 If one or more EADS servers are isolated.

To Page Top

(4) Install and set up the EADS servers to be added

Install and set up the EADS servers you want to add. For details about how to install and set up EADS servers, see 5. Installing and Setting Up (EADS Servers).

There is no need to create cluster property files because these files are created automatically when EADS servers are added (if a cluster property file already exists for an EADS server to be added, that cluster property file is not imported).

To Page Top

(5) Add an EADS server to the cluster

Execute on an EADS server to be added the ezstart or ezserver command to add it to the cluster.

The following are the methods for adding an EADS server to a cluster:

Adding an EADS server to a cluster by specifying its EADS server ID
- Execute the ezstart -ai command on the EADS server to be added.
- Execute the ezserver -ai command on the EADS server to be added.
Adding an EADS servers to a cluster by specifying the EADS server position (hash value)
- Execute the ezstart -ap command on the EADS server to be added.
- Execute the ezserver -ap command on the EADS server to be added.

Adding an EADS server to a cluster by specifying its EADS server ID (executing the ezstart -ai command)

ezstart -ai EADS-server-ID

Adding an EADS servers to a cluster by specifying its EADS server ID (executing the ezserver -ai command)

ezserver -ai EADS-server-ID

Adding an EADS server to a cluster by specifying the EADS server position (executing the ezstart -ap command)

ezstart -ap EADS-server-location-(hash-value)

Adding an EADS server to a cluster by specifying the EADS server position (executing the ezserver -ap command)

ezserver -ap EADS-server-location-(hash-value)

If the cluster property files have not been updated for some reason after an EADS server has been added, an error message is displayed. In such a case, execute the eztool listconf command to check the most recent parameter values and apply those values manually to the cluster property files.

To Page Top

(6) Verify that the added EADS server is participating in the cluster

Execute the eztool status command to verify that the added EADS server is participating in the cluster.

eztool status

Command execution example

[Figure]

If an EADS server is participating in the cluster, online is displayed in the Cluster column.

You add multiple EADS servers by performing for each EADS server to be added the procedure that follows 11.1.1(4) Install and set up the EADS servers to be added.

To Page Top