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Why Disk Has Forever Replaced Tape as a Primary Backup Target

Right here, right now, it’s time to state what may sound preposterous to some and obvious to others. Disk has officially forever replaced tape as the primary target for backup software. But it is for reasons that go much deeper than disk simply now being cheaper, faster and easier to manage than tape. Disk is part of a new backup equation where backup solutions are expected to deliver near real time business continuity and disaster recovery.
The Four Advancements Driving Disk’s Adoption
Small and midsize enterprises (SMEs) that still use tape as their primary backup target are probably aware that disk has made inroads in replacing tape. However tape’s reign as a primary backup target is essentially over. Consider these four major technology advancements that have contributed to disk firmly establishing its preeminence over tape going forward.

  • Hard disk drive (HDD) capacities and cost. HDD manufacturers have delivered on forecasted but still hard to believe increases in storage capacities over the last 10 years. In that time, the size of SATA HDDs have increased from about 40 GBs to their present size of 4 TBs, essentially doubling in storage capacity about every 18 months.

The price for the physical disk platter has also essentially stayed the same or even dropped over that same period of time such that a 4 TB internal HDD can be obtained for less than $200. This has resulted in the latest 2.5 TB LTO-6 tape cartridge costing as much as disk when comparing disk and tape on price per TB basis.

  • Data deduplication. Data deduplication was THE breakthrough technology that enabled disk to begin to replace tape as a primary backup target. This has also resulted in disk becoming more affordable than tape as it gives disk a property of tape: “infinite capacity.

One of the few remaining arguments for tape is that a tape library will technically never “run out of capacity.” As soon as a tape cartridge fills up it can be replaced with another tape cartridge. However, since up to 97% of the backup data in most businesses is a replica of the data from the previous day’s, week’s and month’s backup, by deduplicating this data businesses essentially get this property of tape when they use a solution that deduplicates data.

Affordable data deduplication is now readily available from providers such as Eversync whose disk-based backup solutions achieve deduplication ratios of 10x or greater. For example, using its deduplication solution in conjunction with fifteen (15) internal 4 TB HDDs, SMEs can potentially achieve effective backup storage capacities of over 600 TBs which, from their perspective and at this stage of the game, meets their definition of “infinite capacity.”

  • Replication. Disk’s immobility was another long term road block to disk’s broader adoption. After all, what good is a backup on disk if your building with all data in it is destroyed? But this hurdle too has been overcome in the last few years in large part because of enhancements in replication.

For instance, more replication technology now replicates only changes to the data. Once an initial full copy of a company’s backup data is replicated offsite, only changes to that data need to be replicated going forward. Deduplicating this backup data before it is replicated further reduces the amount of data that needs to be replicated as only one copy of all new data is transmitted to the secondary site. This minimizes the size/bandwidth of the WAN connection that SMEs need to replicate the data and they may even be able to use an existing WAN connection to perform this task.

To overcome the time and bandwidth requirements associated with replicating the intial copy of the backup data offsite, backup solutions now offer removable drive vaulting. Using this technology, a copy of the backup data is made to local media (disk or tape) sent to the remote site and then restored. Once restored at the remote site, the backup solution re-syncs the data between the primary and remote only sending over what data has changed in the intervening time.

  • Improvements in backup software technology and licensing. Even with these prior three factors in place, if backup software could not: 1) backup or recover from disk; 2) manage backup data once it is on disk; or, 3) only did so at a price that was cost-prohibitive to most SMEs; it would still be premature to declare that disk had replaced tape as a primary backup target.

This is not the case as backup software from providers such as Eversync illustrate. It backs up and recovers from disk.  It can manage the replication of backup data between two sites. All of its backup, data deduplication, recovery and replication features (along with many others) are included which SMEs find easy to understand.

The Intangibles Driving Disk’s Adoption
Yet these four technical reasons as to why disk has replaced tape as a primary backup target fail to account for many of the intangible reasons that are also driving disk’s adoption. What do not appear on any ROI spreadsheet are the dramatic improvements in personal quality of life and peace of mind that every individual who has adopted disk as a backup target shares with me.
Disk eliminates the daily grind and uncertainty that typically surrounds backup to tape. In its stead is a new found sense of relief that backups and restores are completing successfully and more quickly with the worries that administrators have about backup jobs failing largely coming to an end.
IT staff is no longer bogged down for hours each day troubleshooting problems associated with failed backup jobs. Rather they may turn their attention to satisfying the real needs of the business which center on recovery. People want to recover their files, emails, databases – whatever – in seconds or minutes, not hours or days. Using disk as a backup target, they can deliver on those requirements.
Finally, in today’s era of Big Data, even SMEs need affordable disk-based solutions to store their data for longer periods of time to satisfy growing compliance requirements as well as use it to do data analytics. So in addition to having the flexibility to use their backup data for recovery, they may also use that data to better understand their business and identify new business opportunities.

Disk Has Changed the Data Protection Equation

A formula that summarizes this new environment can be stated as follows:

Disk + Deduplication + Replication + Backup Software =
Near-real Time DR & BC

This is the new equation that is replacing data protection now and in the future. The software, hardware, technology, money and staff that were once used to deliver “just” data protection can now be repurposed and refocused to deliver on more strategic disaster recovery and business continuity initiatives.
The reasons as to why disk is replacing tape as a backup target go much deeper than disk just now being cheaper, faster and easier to manage than tape. Over the last decade, an entire cast of supporting technologies has also emerged that make it feasible for disk to replace tape as disk-based solutions now offer benefits such as infinite
capacity, portability and manageability that only tape once offered.
But the real reasons as to why disk will replace tape as a primary backup target may have nothing to do with either the financial or the technical reasons. Rather, they may have everything to do with intangible human reasons as the SMEs and the administrators who work for them want:

  • Less risk and pain in their environment
  • Guarantees that what they have works
  • Time to focus on initiatives that add more value to the business

Editor’s Note: This entry originally was published on February 22, 2011, but was updated and re-posted today to reflect changes in technology.


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