Could a snapshot plug your backup window?
Sounds satisfying, doesn't it
VMworld Europe Talking with Dmitri Joukovski, product management VP at backup firm Acronis, we were discussing backup and snapshots and I asked whether backup was still the best choice. He turned the conversation around and asked me what is backup?
I said it was the collecting of the current set of files on a system, putting them into a single container file and writing that file as if it was going to a tape device. That got me a sigh, and a correction: "Backup is making a copy of data, adding some metadata, and keeping it somewhere close."
Then came a kicker: "Snapshotting can be used for this and in no way contradicts the fundamental operation of backup."
He hammered the point home by saying that Acronis' True Image Backup product uses software snapshot technology already and was "created two or three years before Microsoft created Volume Shadow Service;" VSS creating a point-in-time snapshot of a logical drive.
Joukovski said hardware snapshots, performed by storage array controllers and thus imposing no burden on server resources, were specific to the storage array supplier. You can't recover a NetApp snapshot to a VNX or CLARiiON array.
For them to be generically useful to end-users they would need to be made generic. End-users would want the same functionality with a heterogeneous array snapshot-based backup product.
For example, an Acronis backup of a physical or virtual server can be restored to a physical or virtual server with no restriction to a single server supplier. Hardware snapshots are supplier and product line specific.
If they could be made multi-vendor than a hardware snapshot-based backup product could abolish server-based backup windows because a server-based application wouldn't be running backup code.
Nor would a media server. The backup code, if it existed, would merely issue commands to the storage array, Dell EqualLogic, NetApp, EMC, whatever, to take a snapshot and send it to an Acronis, in this hypothetical case, backup data store where point-in-time snapshots would be stored, ready for restoration to some target array. It would be converted on restoration to the target device format, and thus restoration would involve CPU cycles and take some amount of time longer.
What an enticing prospect. Is Acronis working on this? Joukovski said Acronis doesn't support hardware snapshots in its products, and wouldn't comment on possible developments.
The whole direction of Acronis' backup development is to make backup easier, faster and more convenient. Laurent Dedennis, Acronis' EMEA EVP, talks of the company's virtualisation backup software being able to automatically discover virtual machines and back them up without having to have agent software installed in them.
For an SME customer facing virtual server sprawl this is a good way of protecting the data used by user-created virtual machines without imposing backup process restrictions. The idea of using storage array hardware snapshots, with possibly continuous or near-continuous data protection and, by doing so, drastically shortening or eliminating backup windows, is in tune with this trend, and it would surely have a huge appeal. Will it happen? Ask Acronis. ®
Having used Acronis software and had some experience of their help desk I wouldn't believe a word they said to me. I'd rather they fixed their software and responded to questions instead of arguing the differences between backups and snapshots.
What you need....
....is an application aware snapshot! If only there was a storage vendor that had these baked in to OS, with software that quiesced the application in question, and provided the ability to replicate them off site, and vault them for long term retention....
By the way, I work for NetApp.. ;)
Are Snapshots Backups?
When you back up something, you copy it somewhere else for safekeeping. That's sort of the point.
Taking snapshots is more like generating patches using diff - you still need the original for them to be useful. That's more like a journal or redo log, not like a backup at all.
Snapshots + off-site replication fixes that (indeed, my Bacula setup uses VSS to take consistent backups of Windows filesystems), but snapshots in themselves are not backups.