Can Snaps and Replication ever replace traditional back-up applications? It's an interesting thought and certainly one that we've considered in the past. We often find that the answer that you get very much varies from what the favourite technology is with generally the NetApp fans saying yes and the EMC fans saying no.
Now as a storage agnostic, my answer is maybe but it depends on what you use your back-ups for and your internal processes. I can certainly think of a use case where the answer is NO.
One thing which we do and I suspect many other people do is to use our back-ups as source-data for development copies. So we have to get that data into another environment which may sit on different disk technologies and it's certainly a different environment. Using traditional tape or even VTL based environments, this is relatively easy to do but with a snap-based environment; this will be a lot harder, not impossible but it actually adds complexity.
And if you go down the snaps/replication route; you've made your migration path away from your disk supplier infinitely harder. Because not only are you going to be migrating your primary disk environment but you have tightly coupled your back-up environment to your primary disk environment.
So I would still plump for keeping my back-up environment fairly loosely coupled as opposed to tightly integrated.
I don’t know if you’ve seen systems like the Falconstor CDP and NSS products? I assume you’ve seen either it or one like it like Lefthand (disclosure, I work for a Falconstor reseller).
The CDP and NSS products are both essentially attempts to decouple the snapshot type backup solution from the array itself, providing the snapshot functionality you’d expect from a NetApp or other high-end disk array but works with pretty much anything from cheap no-brains iSCSI arrays right through to high-end FC stuff.
http://www.falconstor.com/en/pages/?pn=CDP
They have a gateway product that sits in the middle between the servers and the disk arrays (like an IBM SVC), or you can use software agents which basically create an additional iSCSI connection to the Falconstor box. I’m sure the HP Lefthand virtual SAN solution can do a very similar job.
It’s not the right solution for everyone, but it’s one way of providing snapshot backup functionality without locking yourself into 1 disk supplier.
“Using traditional tape or even VTL based environments, this is relatively easy to do but with a snap-based environment; this will be a lot harder, not impossible but it actually adds complexity.”
I’m not sure I understand this comment at all, especially in reference to NetApp (since that’s the example you used). So lets talk about SnapManager for SQL and FlexClone + other specific application SnapManagers to provide exactly this – simple, quick and easy – with the option to create multiple copies as incrementals (and minimal capacity utilised), or if required, create a whole new copy, on same/seperate disk, or even seperate array. First two are much quicker than any (B/U) restore function and is wizard based. I don’t know how much simpler this gets…???
Are you completely unaware of these tools? It’s not just koolaid – my customers use it.
And yes, if you wanted to keep all (B/U) copies on disk – then NetApp with application consistent snapshots are indeed good enough for a backup strategy. Again I have customers doing this and are very happy. To clarify, I do not suggest and neither does anyone else I know, that the initial snapshot (on the same array, on the same disk) as a complete backup strategy – this is foolish. I do however have to concur with the vendor lock-in comment.
Paul, did you actually read the line ‘So we have to get that data into another environment which may sit on different disk technologies’?
We run in a heterogeneous environment; development disk may be on completely different arrays from another vendor. It could be that we’ve decided to stick it on dumb disk, it could be DAS, it could be another vendor’s NAS. So many vendors come at a problem assuming that they are the only vendor in an environment…this is rash and unhelpful often.
Hi Martin,
I understand and yes re-reading, I unintentionally took those comments out of context…
I think they can, but they come with one fundamental limit – you only need one tape juke box, and can send your tapes offsite to store.
We do a lot of our recoveries from snaps on our filesystems, and replicate to a DR site, but we still make backups every night, and send the tapes away.
Part of that is ‘being conservative’, but it’s also a degree of practicality – our monthly backups are unlikely to be used, and so there’s not really a lot of point stashing them on spinning disk. But we have compliance requirements that mandate years of retention, despite that practically speaking after that period of time our chances of actually -finding- anything are pretty low.
I’d say you can deal with your ‘normal’ day to day backup, archiving and DR with snaps and replication, but I don’t think you’ll ever quite get away from the need to be able to ‘destage’ a data set for offsite storage.