DRJ Fall 2019

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Fall Journal

Volume 32, Issue 3

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There’s nothing like a hardware or database failure to ruin your day – and your reputation as an IT professional. Losing access to your data for an hour, a day, or more, can set your business back, infuriate users, and cause significant risk to your company’s reputation and bottom line. Data backups are a critical IT function that no business can afford to be without. In our knowledge-based economy, your corporate data must always be available and accessible. As your data and IT infrastructure grow, so does the vulnerability of your business. Protecting your business from that vulnerability is one of the key functions of IT.

With the growing dependence on virtualization as a way to manage IT costs and consolidate infrastructure, the amount of data at most companies is continuing to grow at exponential rates. Traditional tape-based backups simply cannot keep pace. Disaster recovery scenarios risk potentially dangerous shortcomings if the data back-up strategy is based solely on traditional tape backup.

Tape Data Backups Far From Perfect

For years, tape backups have been the least expensive way to protect your data. Although tape is a viable method for archiving and meets regulatory compliance requirements, tape backups have some disadvantages.

First, tape is mechanical by design. Its reliability is questionable, and tape backups are labor intensive and subject to human error. When information is written to tape, a thin piece of plastic ribbon is stretched, pulled, and magnetically imprinted. Repeat this process a thousand times, and it is apparent why a recent Storage Magazine survey noted that more than 60 percent of IT professionals experience tape failure at least once per week and 25 percent at least twice a week.

Second, because tape backup is a slow, labor-intensive process, it often results in longer-than-expected backup timeframes, which in-turn costs your firm productivity. At the same time, data volume is growing, and back-up windows are shrinking because businesses have no tolerance for downtime. When data backup takes too long, recovery point objectives (RPO) are at risk.

Third, data on tape can only be accessed sequentially, adding considerable time to any exploration of a data recovery point. This type of inefficient and labor intensive process ends up adding to your business overhead. Data restores also take a long time. You need to factor in the time to find the correct tape, recall the tape from your bonded offsite storage provider, catalog the tape, and then face the ultimate question ... is the tape still good or not? Software for back-up operations can have issues when interacting with media. Running multiple jobs simultaneously can cause locks, human failure to change tapes can erase historical backups, and resource contention can occur due to unforeseen events or because of a lack of planning on the part of data center operators. Let’s not forget that tape drives can cause problems with tape media.

Finally, tape backups may be incomplete. Businesses make the common mistake of thinking all their back-up policies are 100 percent, assuming complete data resides on their data backups. It often doesn’t. Business data is often left unprotected because the tape back-up process does not include infrastructure level saves, includes all application tiers or, worse, no nightly full saves. Tape backups limit your RPO. Periodic tape backup guarantees hours of lost data in the event of a disaster. If a critical system fails anytime today, the best you can do is recover data from your last backup, which could be from yesterday. In addition, any data not backed up is lost forever. This can mean a significant delay in meeting your RPO and RTO (recovery time objectives). With failed tape backups, your deliverable RPO of 24 hours can quickly become 48 or – worse – 72 hours.

Advantages of Disk-Based Backups

With business operations so reliant on a complete data backup and recovery strategy, it’s vitally important to identify alternatives to tape-based backups that can eliminate vulnerabilities and provide effective data protection that will quickly restore business operations in the event of a failure. Disk is very well suited for backup, especially now with technologies such as de-duplication which offers simplification and cost savings at a relatively low cost. Disk-based backups with block level compression and de-duplication make backups more efficient and reduce storage cost compared to traditional back-up solutions.

Data de-duplication (a specialized data compression technique for eliminating coarse-grained redundant data) is now a common feature across all disk back-up products, with practically every major enterprise data storage vendor offering at least one data de-duplication product. De-dupe takes the redundancy out of backups and back-up data. The problem de-dupe addresses is that backups consume disk space like a vacuum consumes dust.

For example, let’s say you have a terabyte of data and you back it up daily (seven times/week). That’s 7 TB of disk space, despite the fact that less than 10 percent of the data has actually changed. All backups have duplicate data from one backup to the next. With de-duplication, you can shrink that volume significantly by backing up only data that has changed since the last backup. It results in some staggering savings. In our example above, let’s assume a change rate of about 7 percent of the data in each back-up set. The first full back-up set was reduced by a modest percentage to 690 GB. Subsequent full backups were significantly reduced, given their overlap with data in the initial full to about 40 GB each. The total disk requirement for storing 7 TB of raw back-up data was a mere .970 TB. Further, backups to meet your retention policies yield even better results.

If you back up less data, you’ll achieve an automatic reduction in back-up windows. The software takes care of de-duplication at the source. Imagine telling your network administrator you could reduce traffic by 95 percent through de-dupe! Disk-based data back-up solutions have proven to be more reliable than tape, especially when implemented with a RAID system on your SAN. This has the ability to further increase storage integrity and availability through disk redundancy. With disk and de-duplication software, organizations can reduce the back-up process by several hours nightly and reduce the volume of data that has to be transported across the WAN. Combine this with cost and ease of use advantages and you’ll see why organizations are increasingly switching to disk back-up solutions.

Disk Backups Provide Optimized Recovery

Disk-based backups should be a critical component of any business disaster recovery plan. Disk backup ensures the urgent and safe recovery of data in the event of a disaster on any scale. Data security has always been a high priority issue for businesses, but storing data on back-up tapes presents significant risks. Tapes get lost, stolen, and even fall off the backs of trucks. Disk backups are more secure. By storing backup and legacy data in a data vault off-site, you significantly reduce the risks associated with same-site data storage while maintaining the ability to achieve fast, reliable access and recovery when required. Disk backup also enables compliance with corporate governance regulations and situations where liability and accountability are vital.


Tape has, in the past, been an IT firewall, the backstop for data loss in the event of a catastrophic event or disaster. There is still a need for recovery using tape in various tiers of your IT infrastructure. It shows little sign of giving up this position to spinning disk anytime soon. But the need to achieve measurable daily results and maintain greater data protection options has led to a current trend toward disk-based backups being adopted among small, medium, and large businesses alike. The capabilities, operational benefits, scalability, and cost benefits of disk back-up systems make them something every IT shop should consider. After all, you cannot buy your data on the street after a failure.

Richard Dolewski is chief technology officer and vice president of business continuity services for WTS. Dolewski is a certified systems integration specialist and disaster recovery planner and is globally recognized as a subject matter expert for business continuity for IBM iSeries and i5 environments. An author and frequent technical contributor, Dolewski is a winner of numerous speaking awards including COMMON’s Impact Award and is a member of COMMON’s Speaker Hall of Fame. Dolewski’s book titled “System i Disaster Recovery Planning” is available from MC Press and Amazon.com.