While the amount of data in our organisation has spiralled and the technologies for managing data have moved on, we still back up everything with tape. It is now taking eight to 10 hours a night and I do not trust its reliability. Is there a future for tape back-up?
Disc-based back-up is a faster alternative
Chris Gahagan, senior vice-president, Infrastructure Software, EMC
Relying only on tape for back-up and recovery presents several service level challenges.
- Slow recovery time: tape-based recovery is often too slow to meet business recovery time objectives
- Availability impact: executing regular back-ups to tape is slow, elongates back-up windows and compromises application availability
- Increased risk: tape back-up can be unreliable and, once data is written to tape, there is usually no assurance it is complete or accurate enough to recover business-critical data.
With recent disc storage developments, more companies are moving towards backing up information to disc. Disc-based back-up offers benefits over tape such as faster restore times, higher availability and shorter back-up windows, giving improved performance.
Disc-based back-up offers a compelling alternative to tape as it enables organisations to match the appropriate storage platform to the right information based on performance, protection and availability.
Try remote mirroring as well as tape back-up
Jim Armstrong, storage architect, Standard Life
The problem we all face is that data volume growth is continuing to accelerate and the time we have to back it up is shrinking to zero. To solve this problem requires a complete mind shift from traditional "stop the systems and copy all the data to tape" methods.
Most modern disc systems support remote mirroring, which lets you keep two synchronised copies of your data in two locations for disaster recovery. Companies should also have a snapshot facility to create an instant point-in-time copy of a disc sub-system. This can be used to recover from user errors or viruses, which affect both sides of a mirrored system. If your data is important, you may have three copies: primary, mirrored and snapshot.
However, this does not replace tape. You will need several point-in-time back-ups of your data, as customers may not notice the data is corrupt for several days. You will probably also need long retention back-ups for your auditors and for tax purposes.
One answer is to snapshot your data and copy the snapshot data to tape for longer retention. It is acceptable for this to take eight to 10 hours, as it does not affect live data.
Tape back-up is cheaper for long-term archiving
Guy Bunker, chief scientist, Veritas Software
There is a future for tape back-up. Legal requirements mean data has to be archived for a number of years. Tapes are essential in any disaster recovery strategy as the last line of defence. They are easy to move around, can be taken off-site and can be stored for years.
Back-up is actually about restoring data. How quickly do you need your data back? If the data is for a mission-critical application, technologies such as snapshots, local- and wide-area replication and clustering could be suitable.
In the event of data corruption or problems, applications can revert to the previous snapshot, but this is not a complete copy of all the data, it is just the subset that changes - the blocks affected are copied when a write to is done. This means that multiple snapshots can be taken and efficiently stored on disc, with the ability to browse the contents.
If the application is mission-critical, snapshots might not be detailed enough. For full disaster recovery, a firm should replicate the data to a second site (either synchronously or asynchronously), along with wide-area clustering and failover of the application. Software can reduce the expense by allowing disparate hardware to be used, from both the storage and server perspective.
So the real question is, why are you backing up? And what is it you are backing up? If this is mission-critical data there are new technologies which can create a back-up in a few seconds.
If you are backing up for archival purposes, or as a last defence for disaster recovery, tape is still the most cost-effective medium to store data in the long term.
Try lower cost fixed-content storage alternatives
Colin Clark, corporate cost audit manager, Somerfield Stores
A large proportion of data is fixed content which will never change, yet is required as reference data for corporate governance and knowledge purposes.
Traditional back-up approaches do not address this change in the nature of corporate data. The daily/weekly/monthly back-up cycle is ineffective in operational time and in the long-term protection of corporate data and access to content.
Contract law, data protection, accounting best practice, human resources disputes and many other situations may demand access to, for example, e-mail content that is six or more years old.
A new approach is required where frontline information stores, such as e-mail, are regularly archived to lower-cost fixed-content storage, for example, Network Appliance Snaplock or EMC Centera. This approach increases operational efficiency, including reducing back-up times and, provided the right archive solution is implemented, could speed information recovery.
This combination of operational back-up and content archiving provides a solution to creaking IT infrastructure and the business.
Future is in network attached storage options
Martin Soanes, head of IT infrastructure services, Invesco
Historically, Invesco used tape to back-up everything - twice. One set of tape was kept on site for rapid retrieval of systems in the event of failure and the other was sent off-site for disaster recovery and regulatory purposes. This was a costly and time consuming process. We also found tape to be less than wholly reliable - hence the two back-up copies. We can see this model changing rapidly.
Invesco made its first investment with Network Appliance three years ago and it provides infrastructure scalability and recoverability that is not equalled by tape. In terms of sheer effort, Netapp has decreased our total cost of ownership. Mission-critical data is backed up on Network Appliance Nearstore and we review carefully what is on tape.
Our goal is not to have to rely on tape to restore any part of our data environment. Although we still use tape and will always have a need for it, it will be in a much reduced capacity. In future, we will only use tape as a storage medium off-site for purely regulatory purposes.
This was first published in October 2003