Limitations of Tape-Based Recovery
Limitations of tape-based disaster recovery Although the "premium" of tape-based DR is low enough so every company can afford it, this life insurance policy does little to protect the ongoing health of a business. First of all, tape-based backups don't offer complete protection. Data added or updated since the last backup tape was created will not be recoverable if a disaster destroys both the production database and all on-site journals. If the most recent backup tapes are still on-site when a disaster strikes, they may be destroyed as well, forcing the organization to recover from tapes that may be as much as a week old.Tape-based backups are particularly problematic for organizations that require 24x7 system availability because, in general, applications must be stopped while the data they use is backed up. Even when it is technically possible to "save-while-active," it is often not practical. That's because backup jobs put such heavy demands on disk I/O channels and CPU resources that applications may slow to a crawl while the jobs are running. Possibly even more important, tape-based DR does not protect the continuity of operations during frequent maintenance operations, such as hardware and software upgrades. Thus, traditional tape-based backups don't even do a particularly good job of fulfilling their life insurance role. Another failing of tapes is that they can be used to recover data to only a particular point in time, namely the point at which the tape was created. This typically occurs just once every 24 hours and usually at night. If a data item is corrupted in the middle of the day, as when an operator accidentally deletes a file or a computer virus destroys some data, the best that tape can offer is to restore the data to its state as of the previous night. If the data was updated during the day, those updates will be lost and will have to be recreated manually if possible.
Furthermore, recovering a full data center from tapes can take from several hours up to a few days, which does not meet most organizations' business continuity objectives. In fact, that long of an outage would doom some companies.