SAS Disaster Recovery Policy for SAS® Viya® 3.5

• Background
• Position
• External Systems and Data

Background

Disaster-recovery planning is important for any critical business system, including production systems running SAS® Viya® 3.5. SAS customers should and usually do have disaster-recovery plans for their SAS deployments, SAS applications, and SAS data files. Because the implementation of SAS Viya 3.5 is often highly customized and each customer can have different requirements for replicating SAS content, there is no single tool or process that comprehensively meets all of the SAS disaster-recovery needs.

This position statement assumes that you are familiar with the concepts in the Backup and Restore section of SAS® Viya® 3.5 Administration.

Position

Disaster recovery is not the same as high availability. Though both concepts are related to business continuity, high availability is about providing undisrupted continuity of operations whereas disaster recovery involves some amount of downtime, typically measured in days. This position statement addresses disaster recovery. SAS recommends that disaster recovery be predicated on regular, comprehensive backups, and that disaster recovery processes be validated on a regular basis.

The SAS Viya 3.5 release adds support for restoring from SAS backups to physical or virtual machines with different hostnames and IP addresses from the original environment. This is possible as long as the target environment shares the same deployment topology as the source environment, including:

• operating systems
• user and group identities (UIDs and GIDs in Linux)
• versions of SAS software (including the set of installed hot fixes)
• distribution of SAS software components on the target machines
• tenancy (i.e., whether single or multi-tenant)

Furthermore, user data excluded from SAS backups, including home directories, CAS library definitions, and external data sources must be backed up and restored using alternate means from the SAS backup and restore tools. The Backup and Restore: Overview section of SAS® Viya® 3.5 Administration has details on what is and isn’t backed up by these tools.

As described in SAS Disaster Recovery Policy for SAS® Viya® 3.4, disk cloning continues to be an alternate supported approach to performing full-system backups as part of a disaster-recovery plan. See that policy for more details and caveats for that approach.

A Note about External Systems and Data

A disaster-recovery plan for SAS environments needs to incorporate disaster-recovery procedures for the external systems and processes that SAS uses or depends on. These external systems and processes might be as simple as a DNS server address or more complex, such as another production application exchanging data with SAS processes. Additional considerations include:

• External customer data: Customer data is often located in databases or network-file systems that are external to the machines that host the SAS deployment. Because SAS does not provide tools to back up or restore such data, you must consider data backups as part of your disaster-recovery plan.
  
• External systems and processes: SAS deployments frequently interact with other systems and processes. Thus, a disaster-recovery plan for SAS environments needs to incorporate disaster-recovery procedures for the external systems and processes that SAS uses or depends on. These external systems and processes might be as simple as the use of a DNS server address or more complex such as another production application exchanging data with SAS processes. SAS does not provide tools to address such external systems and processes.