Are cloud storage gateways the new virtual tape library?

There are a myriad of data protection appliances available, many of which defy the early definition of a purpose-built backup appliance (PBBA). Today, there are at least four types of data protection appliances:

  • (Real) backup appliances: Includes both the backup engine and some amount of storage.
  • Storage/Deduplication appliances: Target devices that are fed by backup/archive software or directly from some production platforms.
  • Business continuity/Disaster recovery (BC/DR) or failover appliances:Similar to backup appliances, but along with the backup engine and data is a hypervisor or other means to resume functionality without restoring locally or via the cloud.
  • Cloud gateway appliances: Similar to storage appliances, they are fed from an outside source but seamlessly offer cloud capacity in what appears to be local disk storage. Cloud gateway appliances somewhat resemble virtual tape libraries (VTLs) from a few years back.

Twenty years ago, everyone wanted better performance and reliability than what tape could offer at the time, but backup software could not directly interface with disk systems. So, some vendors created VTLs, disk systems that appeared to be tape libraries. Backup software knew how to access tape, and thus disk-based backup became commonplace.

Today, many folks want the economics of cloud, but not all backup software can write directly to the cloud. Some vendors are creating cloud gateways, hybrid cloud solutions that present cloud storage as if it were a local disk system. And because backup software now knows how to write to disk systems, cloud-based backup moves several steps forward.

In both cases, the storage market led a data protection evolution to a new medium by way of emulation.

There are some differences, of course. The goal of moving to disk is heightened performance and reliability, while the aim of going to the cloud is an increase in economics and site durability. But economics shouldn’t come at the expense (pun intended) of what disk still brings today in performance/reliability, so good cloud gateways are focused on solving thelatency problem of cloud services through a combination of deduplication/compression within the appliance, as well as serious WAN optimization technology for the network transmission.

To be clear, I’m an advocate of cloud gateways because not everyone is ready to throw out every part of their existing backup solution to go to a backup-as-a-service (BaaS) offering. Instead, folks can extend their data protection strategy to the cloud, while keeping their currently deployed backup agents and backup servers with scheduled jobs. Additionally, staff requires little to no additional training because backup operations remain the same; the cloud gateway drops right into the existing environment.

Like most other IT evolutions, after a few years of this approach, users may choose to move further down that road. But because it’s difficult to imagine any data center-grade cloud solution that doesn’t require a local copy for fast restores, a disk-extended-to-cloud model makes sense for the long haul — and cloud gateways offer that now.

However, because some cloud gateways only appear as disk, the backup software can’t leverage any additional agility or capabilities that come from the cloud repository itself. Some backup software vendors are moving past that and developing software that can write data directly to cloud repositories, much like those vendors that stopped relying on VTL emulation and began writing to disk systems natively. But those solutions must integrate with and manage each medium (local disk, tape and cloud storage) asynchronously.

There is a perception that VTL is an antiquated methodology that doesn’t wholly utilize the features of the native medium (disk), but it’s still widely deployed. It took 15 years for VTLs to be mostly displaced by native disk access methods (CIFS, NFS and API), but it’s unlikely backup vendors will take nearly that long to fully embrace cloud-access protocols.

So the questions for cloud storage gateway vendors are as follows:

  • Can you offer gateways with deduplication that is on par with other local disk solutions and differentiate your products with features such as superior WAN optimization?
  • Does your product offer optimized local storage, and also fully enable the utilization of cloud storage features?

Vendors that don’t innovate beyond the initial emulation scenario should expect the same long-term fate as VTL. For those that do continue to innovate with ever-broadening cloud-centric integration features in mind, gateways are as interesting in the long term as they are attractive and immediately usable in the short term.

[Originally posted on TechTarget as a recurring columnist]

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