In the days when companies operated only during standard business hours, nightly backup windows were not impediments, as backups were performed off-hours. But now, business hours have expanded. Many global organizations, especially those that operate Web-based sales and services, operate on a 24/7 basis.
Furthermore, backup jobs often take much longer to run because databases are much larger than they were in the past. Faster tape drives reduce the amount of time it takes to perform the backup, but they do nothing to eliminate the problem of interrupting 24/7 operations.
Even when companies aren't in 24/7 environments, competitive pressures often require them to keep their facilities running longer to better leverage fixed assets. Again, this reduces the backup window. Although it may not shrink to zero as it does for 24/7 companies, it may still be inadequate to facilitate backup operations.
The trouble with tape-based backups
Beyond shrinking backup windows, tape suffers from other problems. For one, despite today's high-speed drives, restoring a data center from tape can take several hours or even days-particularly if the tapes have to be retrieved from a remote location. For most of today's businesses, this downtime can be catastrophic.
Another problem with tape-based backups is that they are created only once a day, usually at night. If a disaster destroys a data center (including any onsite logs), data updates applied after the backup tapes were created will be lost. Further, companies that rely solely on tape backups actually put more than a day's worth of data at risk. Here is why.
While disasters are rare, data losses frequently result from human error, malevolent actions or simultaneous disk crashes that overcome the protection offered by RAID. In these instances, data must be recovered locally, and rapid recovery depends upon having the backup tapes on hand. Consequently, many companies hold the most recent backup tapes on site; they ship yesterday's tapes to a remote backup site only when new backup tapes are created the following night. Thus, these organizations put up to two days' worth of data at risk.
It doesn't end there. Tape is fallible. It is estimated that as many as 25 percent of the attempts to recover data from tape are less than completely successful. Thus, an organization may lose three or more days' worth of data if the most recent backup tape is still onsite (and the most recent offsite tape is unreadable for some reason when a disaster strikes).
Security is another issue. Being a physical medium, tape is vulnerable to theft. If the data on it is not encrypted, it could fall into the wrong hands when in transit to (or located at) a recovery site. For these reasons, tape-based backups no longer offer adequate disaster recovery protection for many of today's organizations.