Can snapshots replace traditional backups?
Backup is necessary evil. In IT, every operator, administrator, engineer, manager, and C-level executive knows that you got to have backup. When it comes to the protection of data and information in a business, backup is the only way.
Backup has also become the bane of IT operations. Every product that is out there in the market is trying to cram as much production data to backup as possible just to fit into the backup window. We only have 24 hours in a day, so there is no way the backup window can be increased unless
- You reduce the size of the primary data to be backed up – think compression, deduplication, archiving
- You replicate the primary data to a secondary device and backup the secondary device – which is ironic because when you replicate, you are creating a copy of the primary data, which technically is a backup. So you are technically backing up a backup
- You speed up the transfer of primary data to the backup device
Either way, the IT operations is trying to overcome the challenges of the backup window. And the whole purpose for backup is to be cock-sure that data can be restored when it comes to recovery. It’s like insurance. You pay for the premium so that you are able to use the insurance facility to recover during the times of need. We have heard that analogy many times before.
On the flip side of the coin, a snapshot is also a backup. Snapshots are point-in-time copies of the primary data and many a times, snapshots are taken and then used as the source of a “true” backup to a secondary device, be it disk-based or tape-based. However, snapshots have suffered the perception that it is a pseudo-backup, until recent last couple of years.
Here are some food for thoughts …
WHAT IF we eliminate backing data to a secondary device?
WHAT IF the IT operations is ready to embrace snapshots as the true backup?
WHAT IF we rely on snapshots for backup and replicated snapshots for disaster recovery?
First of all, it will solve the perennial issues of backup to a “secondary device”. The operative word here is the “secondary device”, because that secondary device is usually external to the primary storage.
Tape subsystems and tape are constantly being ridiculed as the culprit of missing backup windows. Duplications after duplications of the same set of files in every backup set triggered the adoption of deduplication solutions from Data Domain, Avamar, PureDisk, ExaGrid, Quantum and so on. Networks are also blamed because network backup runs through the LAN. LANless backup will use another conduit, usually Fibre Channel, to transport data to the secondary device.
If we eliminate the “secondary device” and perform backup in the primary storage itself, then networks are no longer part of the backup. There is no need for deduplication because the data could already have been deduplicated and compressed in the primary storage.
Note that what I have suggested is to backup, compress and dedupe, AND also restore from the primary storage. There is no secondary storage device for backup, compress, dedupe and restore.
Wouldn’t that paint a better way of doing backup?
Snapshots will be the only mechanism to backup. Snapshots are quick, usually in minutes and some in seconds. Most snapshot implementations today are space efficient, consuming storage only for delta changes. The primary device will compress and dedupe, depending on the data’s characteristics.
For DR, snapshots are shipped to a remote storage of equal prowess at the DR site, where the snapshot can be rebuild and be in a ready mode to become primary data when required. NetApp SnapVault is one example. ZFS snapshot replication is another.
And when it comes to recovery, quick restores of primary data will be from snapshots. If the primary storage goes down, clients and host initiators can be rerouted quickly to the DR device for services to resume.
I believe with the convergence of multi-core processing power, 10GbE networks, SSDs, very large capacity drives, we could be seeing a shift in the backup design model and possible the entire IT landscape. Snapshots could very likely replace traditional backup in the near future, and secondary device may be a thing of the past.
Posted on August 5, 2011, in Backup, Disks, Snapshots, Tapes and tagged backup, point-in-time, primary storage, secondary storage, snapshot, space efficient, SSD. Bookmark the permalink. Leave a comment.