Posts Tagged ‘Backup’

The Human Factor in Consistency Groups

What’s worse than losing your data?

Losing your data and having no backup.

What’s worse than having no backup?

Having a backup that restores inconsistent data.

That’s precisely the concern that Josh Kirsher raised on the April 10 Wikibon Peer Incite. A lot of people are buying insurance, in the form of snapshots of application data, and they leverage consistency groups, thinking this will insure that the data is application-consistent. It’s the application-consistent snapshot that companies use as source-volumes for off-site backups and asynchronous replication, and as on-premise application recovery points. And it’s consistency groups that enable applications to be restored in minutes rather than hours or days. Unfortunately consistency groups only work when procedures are perfectly designed, when they are perfectly followed, when they are constantly maintained, and when no one makes an error.

In today’s dynamic environment, where the servers on which applications run are virtualized, where applications are frequently moved from one physical server to another, where LUNs are quickly created, and volumes are added to and removed from LUNs on a daily basis, the probability of developing a perfect consistency-group process that is precisely followed and continuously maintained, without introducing any human error,  is very low. That means that, when you need to call upon your insurance, which is the snapshot or the backup that you assume is application consistent, the probability is very high that the data will in fact be inconsistent and the time to restore consistent application data from paper source documents will be measured in days, not minutes or  hours. And, for companies that primarily transact business electronically, they may not be able to reconstruct the data at all. This is the scenario that Tim Hays, of Animal Health International, avoided when he made the decision to protect everything. After all, if  he could affordably protect everything, he didn’t have to worry about what he might miss.

There is a Better Way to Move Data Over Distance

Early this year, Batley News in the U.K., reported that Cattles Group, a financial services company, was being investigated, after the firm lost the personal information belonging to a million people, including both customers and employees. You can read the entire article here, but the lost data was on two tapes that went missing. It doesn’t mean that they got in the wrong hands, and it doesn’t mean that the data has actually been accessed by an unauthorized person, or that accounts have been compromised. But under a number of laws that exist in various countries, losing personal information that has been entrusted to an organization is a reportable offense. And so, Cattles Group notified the police and two other government agencies.  And they also notified each of the affected customers and employees.

Despite the continued decline in the use of tape, it is, in fact, still in use, and there are a number of applications where tape remains very valuable and a great technology fit.  Two of the historical values of tape were that it was removable and transportable. And one tape holds a lot of data. Remember, two tapes held the personal information of a million people. The fact that tape is removable and transportable is also its  liability. So it is not unusual to hear incidents of lost tapes and, thus, lost data. In fact, there is an entire website, datalossdb.org, devoted to reporting data losses, and you can search the database for data losses associated with tape media.

If the job of the solution is to get your data from one location to another in a secure and cost-effective way, so that you can restore operations after a disaster, I think the improvements in disk-based replication technology, including point-in-time, application-consistent snapshots, data deduplication, and data compression, make it unlikely that tape will survive much longer as a backup media. Add to that Axxana’s zero-data-loss-over-any-distance capabilities and there’s no compelling reason to stay with tape.