Data Management Glossary
What is Secondary Storage?
Secondary storage devices are storage devices that operate alongside the computer’s primary storage, RAM, and cache memory. Secondary storage is for any amount of data, from a few megabytes to petabytes. These devices store almost all types of programs and applications. This can consist of items like the operating system, device drivers, applications, and user data. For example, internal secondary storage devices include the hard disk drive, the tape disk drive, and compact disk drive.
Some key facts about secondary storage:
- It is typically designed for long-term storage – its non-volatile media such as solid state devices, optical or magnetic storage devices such as tape.
- It is typically orders of magnitude cheaper than primary storage – it is designed for more capacity storage than performance.
- It can either be hosted on-premises at data centers or in the cloud.
- It can use file (Network Attached Storage NAS via NFS and SMB/CIFS protocols) or block-based storage-area-network (SAN) or object formats. Object-based secondary storage is extremely popular today especially in the cloud.
- Examples include: Amazon Simple Storage Service (S3), Amazon Glacier, Azure Blob, Google Cloud ColdLine Storage, and on-premises object stores such as IBM Cloud Object Storage.
- Use cases include: Cold data storage, Cold data tiering or data archiving, data backup and Disaster Recovery storage.
- Data management software is used to find the right data to place on secondary storage and move data to secondary storage without user disruption.
Secondary storage typically tiers or archives inactive cold data and backs up primary storage through data replication or other data backup methods. This replication or data backup process, ensures there is a second copy of the data. In an enterprise environment, the storage of secondary data can be in the form of a network-attached storage (NAS) box, storage-area network (SAN), or tape. In addition, to lessen the demand on primary storage, object storage devices may also be used for secondary storage. The growth of organizational unstructured data has prompted storage managers to move data to lower tiers of storage, increasingly cloud data storage, to reduce the impact on primary storage systems. Furthermore, in moving data from more expensive primary storage to less expensive tiers of storage, knowns as cloud tiering, storage managers are able to save money. This keeps the data easily accessible in order to satisfy both business and compliance requirements.
When data tiering and archiving cold data to secondary storage, it is important that the archiving / tiering solution does not disrupt users by requiring them to rewrite applications to find the data on the secondary storage. Transparent archiving is key to ensuring that data moved to secondary storage still appears to reside on the primary storage and continues to be accessed from the primary storage without any changes to users or applications. Transparent move technology solutions that use file-level tiering to accomplish this.