Virtual Tape Libraries: Advantages and Disadvantages

Virtual Tape Libraries (VTLs) are long-term storage solutions that simulate data tape hardware while using an array of hard drives (HDDs) for the actual storage.

Many organizations have established processes for handling data archives. Enterprises may be reliant on certain backup software or recovery processes, which makes traditional tape migration impractical or undesirable. 

A VTL offers a “best of both worlds” middle ground; the organization can retain their current backup/archival strategy while improving efficiency and reducing the time spent on data restoration. The VTL can be coordinated with traditional tape backups to reduce the physical space utilization of onsite hardware.

Of course, if virtual tape libraries were perfect, there would be no reason to use actual tape cartridges — but physical tape libraries continue to capture market share from HDD-based systems. 

But VTLs make sense for many organizations, particularly enterprises with relatively well-defined backup/archive protocols. Below, we’ll discuss some of the major advantages and disadvantages of VTL utilization.

Advantages of Virtual Tape Libraries: Faster Restoration, Lower Deployment Costs

Generally, VTLs have lower initial deployment costs than new tape hardware, although the cost of implementation can vary. VTL solutions can function with all popular backup/archival applications, and the enterprise won’t need to change its practices to put the new system to use.

Other major advantages of VTLs:

  • The entire storage capacity of the disk array is available.
  • RAID can provide several layers of redundancy, but with optimal data deduplication for better overall storage utilization.
  • Hard drives are generally more efficient for read processes than legacy tape cartridges, especially when utilizing RAID. 
  • VTL can significantly reduce disaster recovery time, particularly when compared with legacy tape formats.
  • VTLs support random access, while most legacy tape formats only support sequential data access.
  • In crowded datacenters, VTLs may utilize physical space more effectively.

But while virtual tape libraries are effective for many applications, they’re not without their faults — and advances in tape storage technology have nullified some of the benefits.

Disadvantages of Virtual Tape Libraries: Less Resiliency, High Long-Term Costs

One of the major advantages of tape is air-gapping, which provides protection against ransomware and other data security hazards. An air-gapped backup can be isolated from the rest of the data storage infrastructure, ensuring that the enterprise has a recovery option in worst-case scenarios. 

VTLs are not air-gapped, nor are they intended to be transported outside of the data center; the VTL essentially acts as an onsite archive. High-capacity tapes can be easily taken off site or offline, so they’re ideal for creating “golden copies,” which are crucial for protecting against malware. 

Other advantages of data tape cartridges over VTLs:

  • Current tape cartridge formats are significantly less expensive per-gigabyte than hard drives. At the time of writing, LTO-9 has a cost of about $0.0058/GB, and that price will continue to decrease in future generations.
  • Modern tape cartridges can utilize file systems such as LTFS to mimic random access (though it’s worth noting that “mimic” is a key phrase — LTFS, while powerful, is still limited to the physics of the tape cartridge). 
  • In most operations, VTLs are not a full replacement for tapes; they’re intended as a complement to tape infrastructure. As a result, disaster recovery may not be any faster with a VTL in place — and the complexity of VTL implementation may actually add to the time needed for recovery.

Creating a Strategy for Data Archiving and Disaster Recovery

Ultimately, most enterprises require a combination of VTLs and physical tapes. To optimize the benefits of VTLs or physical tapes, the storage infrastructure must be designed for the organization’s specific needs. Any new implementation must be planned carefully, particularly if the goal is to limit tape hardware or to migrate away from a certain tape format.

If you’re considering a switch to VTL, or if you’re looking for ways to optimize your backup/archival processes, Total Data Migration can help. 

With an extensive library of tape hardware, access to hundreds of current & legacy backup applications, and decades of experience, we create sustainable, cost-efficient strategies for data migration. Contact us today to schedule a consultation.