Key storage choices: Cloud vs tape for archive storage?

Tape still has benefits, such as an “air gap” that can insulate archives from threats to data integrity. But what are the opportunities for cloud in tape’s traditional use cases?

Tape continues to play a role in the enterprise, and not just because it is a tried and tested technology in backup and archive. Tape has attributes that set it apart from other media. This continues to apply, even as more enterprises move data to the cloud.

Magnetic tape has been around since the 1950s, yet it’s still a key component of data backup and recovery, and archiving. These are applications where offline storage is an advantage, rather than a disadvantage.

Tape is uniquely suitable for offsite storage, as the media itself is lightweight and more robust in transit than the hard drive. The way tape operates, with the data separated from the read/write mechanism, creates a natural “air gap”.

 This air gap is one reason tape continues to find favour with storage and disaster recovery experts. A completely separate data store is resilient against problems caused by code errors or other problems with production applications.

Increasingly, organisations are also turning to tape because it offers a fairly high degree of protection against ransomware.

Online or near line systems are vulnerable to the same malware that targets core production systems. If tape storage is managed well, it should avoid cross-infection by ransomware payloads.

Cost Advantage

Cost, too, is an advantage for tape. Hard drives and solid-state storage continue to fall in price, and capacities have now reached 16TB per disk. But tape storage has no theoretical limit, as long as the user has a robust system for managing and storing the cartridges. Most businesses today use LTO-based tape.

And, whilst tape systems remain relatively expensive to buy – an issue especially for smaller businesses – the incremental cost of adding capacity is far lower than on a disk-based array. A latest-generation LTO-8 tape stores 12TB, which rises to 30TB with compression. This works out at about 0.4 pence per GB.

Media costs, once the business has bought tape drive hardware, are low. Running costs are a further factor in tape’s favour. Disk- and flash-based systems need power and cooling. Tape will last longer in a climate- and moisture-controlled environment, but it can be stored in an office. These low lifetime costs makes tape suitable for long-term data storage and archiving in a range of industries, including financial services, oil and gas, research and media. Even so, more industries are looking to the cloud for archive storage.

Cloud

But not all backup products can integrate directly with cloud storage, and not all work the same way, which can cause application compatibility and operational issues. Data managers need to ensure their business applications, backup products or services and cloud providers are compatible, and offer the right service-level guarantees.

Cloud services have other disadvantages too. The first, surprisingly, is cost.

Although the cost per GB is low, cloud-based storage incurs monthly or annual fees. These can quickly add up. Then there are additional “bandwidth” charges for accessing or restoring data.

Although it is hard to generalise across all businesses, storage consultants ProStorage calculate that cloud storage is generally viable for organisations that store up to 50TB for the long term. Above that, scale economies favour tape. This reflects the up-front cost of tape storage hardware, as well as the on-going cost for large volumes of data in the cloud.

Another factor, and one which is as much about practicalities as cost, is the time it takes to move significant data volumes to the cloud.

Data upload speeds over the public network remain a barrier. Smaller or newer businesses, or businesses that already use cloud-based applications, will find it easier to move backups or archives to the cloud. For businesses with substantial data volumes on-premises, phasing in cloud storage, or running it alongside nearline disk and tape, is more practical.

As IDC says, “We don’t say go cloud or go tape, it is more and/or, with technology being driven by the business.”