Requirements

License Information

The pricing unit of AhsayCBS Replication Server module is per device to be replicated. If you will replicate to another AhsayCBS, an AhsayCBS module license will also be required.

Version / Platform Compatibility

While AhsayCBS can be deployed on Windows, Linux, FreeBSD, or Solaris x64 platform, it should be noted that only some of the version and platform combinations are supported as illustrated below.

^* The incompatibility is a result of the limitations on Windows operating systems handling of Linux file/folder naming conventions.

Replication Server Storage Requirement

There is a possibility that after your backup data is replicated to the replication server, the final data size on the replication server may be larger than the original data size on the backup server. This situation could arise if there are differences in the way each respective storage device is formatted, i.e. different default block sizes or different files systems.

Your retention policy settings would also determine the storage required on the replication server. You will need to weigh the advantages of using smaller Restore Point Interval which allows for a greater chance of recovery and or the Retention Customization Policy setting is configured for a large number of days against your replication server storage limitations.

Considering the factors mentioned above, the disk capacity of your replication server should by default be greater than your backup server to accommodate the replication data.

Location of the Replication Server

In terms of disaster recovery situation, the restore media should not be stored or located on the same premises, and these rules would also depend on different compliances, regulations or terms with your customers.

Here are some suggestions that you may need to consider:

Set up the AhsayCBS Replication Server in another data center. In case you need to host the Replication Server with your Backup Server, you may consider hosting it in another server rack or another server room if possible.

Dedicated Server for Replication

Following are the pros and cons on setting up replication on a dedicated server.

Pros

• Able to switch from Replication Server to Backup Server.
• Fast in recovery hence small recovery window and short downtime.
• Able to keep replicated snapshots in retention area in case recovery of data in past snapshots becomes necessary.

Cons

• Relatively more complex setup; requires datacenter hosting and maintenance cost.
• Relatively expensive to expand storage.
• Downtime required for regular maintenance and upgrade.
• Upfront investment in hardware storage.

Predefined Destination (Cloud Storage / FTP / SFTP) for Replication

Following are the pros and cons on setting up replication on a predefined destination.

Pros

• Quick setup; low hosting and maintenance cost.
• Cheaper cost for storage expansion.
• No upfront hardware investment required.

Cons

• To recover the replicated data, it is required to set up new backup server and restore data from the predefined destination.
• Slow in recovery hence large recovery window and longer downtime.

For more information and comparison on different replication environment setup, please refer to Comparison of Different Replication Setup Environment.

AhsayCBS Replication Partitioning

The AhsayCBS replication module makes heavy use of the User Home directory to process the snapshots of the backup sets during the Resync stage. During Resync stage, snapshots of backup sets will be written to the User Home in the form of transactions log files.

It is not recommended to use the O/S partition or drive as the System Home. If the System Home folder fills up, this will cause your O/S to become unstable and may even crash your AhsayCBS server. It is strongly recommended the System Home directory should be located on a dedicated local drive.

Replication Performance Tuning

The connection speed between the backup server and the replication location (whether it is an AhsayCBS server or a cloud storage) is typically the primary factor of the replication performance. However, even with a fast and stable connection between the backup server and replication location, the replication performance could be affected by the following factors:

• Poor disk I/O on the backup server – when scanning and retrieving data files to be sent to the replication server.
• Poor disk I/O on the replication server – when receiving and committing files to the receiver home.

Poor disk I/O can be attributed to:

• The use of network drives as AhsayCBS user and system homes on the backup server side.
• The use of network drives as AhsayCBS receiver home(s) on the replication side.
• The use of a single large disk or volume for AhsayCBS user home.
• The use of a single large disk or volume for multiple AhsayCBS receiver home(s) on the replication side.
• Slow performing local hard drives or storage devices.

In order to improve overall replication performance, the following are recommended:

• A separate local drive for each AhsayCBS user home on the backup server side.
• Distributing user accounts across multiple user homes to balance the I/O load.
• A separate local drive for AhsayCBS system home on the backup server side.
• A separate local drive for each receiver on the replication side.

AhsayCBS Java Heap Size Setting

The machine with the Replication server installed may require more memory for additional feature such as retention policy to run.

• For a replication server with single receiver, a maximum Java heap size setting of at least 1024M is recommended.
• For a replication server with multiple receivers, a maximum Java heap size setting of at least 2048M is recommended.

When setting the maximum Java heap size for the replication server, please ensure this value does not exceed 2/3 of the RAM on the server, to allow sufficient memory for O/S processes and operations.

It is not recommended to set excessively high values for the maximum Java heap size, as this could result in performance issues on the replication server during internal Java VM garbage collection or memory recycling routines.

Firewall Settings

Since replication is performed via the http/https ports defined on the AhsayCBS backup server, after you have finished setting up your replication server, please ensure you have updated your firewall settings to allow network traffic through those ports, which are typically port 80 for http and port 443 for https.