Applying disk to backup hasn't necessarily eliminated tape; but, for some organizations, the cloud could be the answer.
Today, only 20% of ESG research respondents rely exclusively on tape (disk-to-tape or D2T) for their on-site backup process. For on-site backup, 80% of the companies surveyed by ESG have made the transition to a disk-assisted (disk-to-disk-to-tape or D2D2T) or disk-based (disk-to-disk or D2D) backup strategy. And among those using on-site disk, 60% eventually move data to tape for long-term retention or to facilitate disaster recovery.*
Though off-site storage media today is dominated by tape, ESG expects this to change in the years ahead. By 2012, the average volume of data stored on off-site disk and third-party cloud storage is predicted to grow and become increasingly used as an alternative to off-site tape. The volume of data kept in third-party cloud storage is expected to increase nearly fourfold in the next two years, while off-site tape is expected to decrease by one-third by 2012.*
Disk and deduplication driving cloud adoption
Never-ending data growth has been forcing the use of disk in the backup data path to relieve pressure on the limited time available to execute larger and larger backup jobs. The adoption of disk is also being fueled by data storage efficiency technologies, such as data deduplication. So how do these trends impact the interest in cloud?
As IT organizations adopt disk for backup and decrease their reliance on tape media, interest in vaulting data electronically is on the rise. This is especially true for those employing deduplication to optimize network bandwidth and storage capacity. Maintaining data in its optimized state and electronically transferring it within and between sites creates new levels of efficiency. Provided adequate WAN bandwidth, transferring copies off-site is appealing for many companies. That's where the cloud comes in.
The cloud tier
There's a lot of hype (and some confusion) about the cloud. It can play a big role in data protection strategies, but there are slight nuances to its use in these situations. In each case, a copy of data is stored in a cloud container and can be retrieved to facilitate recovery.
- Backup software as a service (SaaS) is when a service provider offers a web-based backup application and cloud-based storage for backup processes. Backup SaaS can leverage pure cloud resources or it can take a hybrid approach and combine some on-premises storage with storage in the cloud.
- Cloud storage services provide a third-party cloud-based tier of storage for on-premises backup and archive solutions. On-premises, licensed backup products integrate with cloud storage providers' APIs to enable the seamless transfer of data into the cloud tier.
- Cloud-based disaster recovery combines cloud compute and cloud storage services to enable failover to a cloud-based instance of an on-premises server.
Risks and rewards
Organizations adopting a cloud tier see it as a tier of storage, unlimited in size, that doesn't have to be directly managed and may provide a more predictable cost model than acquiring, installing, configuring, maintaining and provisioning on-premises backup storage. A cloud tier is also a way to maintain remote copies of data for disaster recovery and may provide a better aggregation point for remote office and branch-office backup data than the corporate data center.
Organizations wary of leveraging a cloud tier often cite concerns about data security, access and control. Once corporate data leaves the physical security of a corporate location, protecting the privacy of the data becomes tantamount. IT administrators therefore need reassurance that accessibility to data stored in a cloud tier -- likely defined in a service-level agreement (SLA) -- meets the expectations of IT as well as those of their business constituents.
There's likely a big recovery time objective (RTO) improvement when recovering individual files or small data sets from the cloud because they can be directly recalled and streamed over the network. The alternative of recalling tape media, and recovering from tape, can take more time. Concerns about meeting RTOs when performing a "bulk" recovery of data are well founded. The time it would take to transfer data for a whole server or site jeopardizes any chance of meeting even the most lax RTOs.
Easing into the cloud
Taking advantage of on-demand cloud storage doesn't have to be complicated or disruptive. Many popular backup applications provide integration with cloud storage services today, including CommVault, EMC, Microsoft, Symantec and Zmanda. It's as easy as combining current on-premises backup software and bandwidth with a subscription to a supported cloud storage service, and modifying backup policies to direct a copy to a cloud target. But getting that first full backup copy to the cloud could be clumsy. For example, the size of the backup set may be too large to transfer over a low bandwidth connection in a reasonable amount of time. That's why most cloud storage service providers offer a "seeding" service that allows data to be uploaded into the cloud via portable media instead.
The easiest use case to trial cloud storage services is remote office and branch-office data. The typical volume of data at remote and branch offices is well-suited to this approach; it's usually transported off site anyway and there's great potential to eliminate on-premises hardware.
*Source: ESG Research Report, Data Protection Market Trends, April 2010.
BIO: Lauren Whitehouse is an analyst focusing on backup and recovery software and replication solutions at Enterprise Strategy Group, Milford, Mass.