Disk-to-disk backup systems help speed backup and recovery processes.
Keeping up with the relentless growth of data is an ongoing struggle for the vast majority of large organizations. In a recent survey of more than 400 IT professionals conducted by data storage firm Sepaton, more than 40 percent reported that their backup times exceed 24 hours. In essence, they are producing data faster than they can back it up.
As backup and recovery operations have become increasingly complex and problematic amid growing volumes of data, these organizations are coming to the realization that their old, reliable tape backup systems are simply too slow to keep pace. While a majority of respondents said they are using physical tape today, most do not expect to be using tape one year from now.
High-speed disk-based technologies such as virtual tape libraries (VTL) have simply become too appealing to ignore. When they emerged several years ago, virtual tape solutions immediately proved popular because they appear as a tape device to the network, avoiding the need for a forklift upgrade. The latest VTLs have even more to offer, however. They are faster, scale higher and offer more flexibility with built-in features such as remote replication and data de-duplication.
“Disk is increasingly being placed in the data protection path to improve upon existing backup processes,” IDC analysts Laura DuBois and Robert Amatruda noted in their recent analysis of VTL vendors. Moreover, the report states that the VTL market is “quickly shifting into a broader disk-based data protection market that includes not only tape emulation and the ability to export to physical tape but also support for de-duplication, remote replication, standard network interfaces, and the ability to become a data protection platform for different backup, archive and recovery workloads.”
Closing the Window
Although virtual tape looks and acts like traditional tape systems to backup applications, it offers key benefits of disk drives, including direct random access, improved read/write efficiency and significant time savings. While enhanced functionality for de-duplication and remote replication have raised the stakes, speed remains virtual tape’s greatest benefit.
Back up sessions that would ordinarily consume a full weekend often can be completed in less than 12 hours with virtual tape. In addition, a disk-to-disk (D2D) system eliminates the need for error-prone tape-rotation processes, reduces the number of tape drives an organization must purchase, limits the physical space required for tape storage, and shrinks personnel costs associated with managing a large tape library.
“Tape-based systems are impractical, expensive and burn up too many tiles in the data center,” said Carl Follstad, Manager of University Data Management Services for the University of Minnesota. “With [disk-based backup] we will be able to shorten our backup windows, therefore allowing us to back up more servers in a shorter amount of time and maintain the highest levels of service to thousands of students, staff and faculty.”
Faster Recovery
Disk’s retrieval advantages over tape are also beyond dispute. Loading a tape to search for a single file to restore from a week-old backup could take hours, while a similar search from a disk might take only a few minutes or less. The difference becomes even more pronounced if a full server restoration is required.
Recovery speed is an essential consideration these days, given the fast-retrieval requirements of federal regulations such as Sarbanes-Oxley and HIPAA. These regulations also require that certain data be stored in a manner that ensures it cannot be altered. A number of vendors have addressed this issue with the development of disks with WORM-like (write once, read many) features that protect data from being altered.
VTLs are also increasingly integrated into tiered storage solutions, allowing organizations to utilize different types of storage media for various categories of data. Tier-1 storage might hold mission-critical or frequently accessed files on primary disk arrays; tier-2 storage might house seldom-used files on less expensive disks; and tier-3 storage might maintain archived files on tape. Because virtual tape is transparent to the host computer and associated applications, organizations can realize the benefits of a tiered storage hierarchy without re-engineering their systems.
Shrinking Data
VTLs also enable data de-duplication solutions that dramatically reduce the amount of data that must be backed up each night, further reducing the backup window. Also known as global compression, commonality factoring, single-instance storage and referential integrity, data de-duplication eliminates redundant copies of data to reduce storage costs and shrink backup and recovery times.
It also makes wide-area backup an operational reality. Since only de-duplicated data moves across the WAN, organizations can securely replicate their data without high bandwidth costs or physical transportation risks. VTLs with de-duplication effectively neutralize what had been tape’s one major advantage — portability — by rapidly and cost-effectively moving data across the WAN to a disaster recovery site, thus eliminating tape shipping costs and risk.
Most industry analysts believe that tape and disk backup solutions will continue to coexist for the next few years. Tape still has its place in the data center — it remains an economical medium for long-term retention for both backup and archive. In the long term, however, tape will become marginalized as a frontline data protection tool as more organizations conclude that virtual tape offers significant advantages in price, performance and reliability.
