Friday, May 19, 2006

FlexVols: Flexible Data Management

If you're managing Storage you're most likely to have experienced some of these issues. Too much storage is allocated and not used by some applications, while other apps are getting starved. Because application reconfiguration is not a trivial process and it's time and resource consuming, let alone it requires application downtime, most folks end up buying more disk.

The root of the problem with data management is that it relies heavily on forecasting and getting the forecast right all the time is an impossible task. Another issue with Data Management is that there are too many hidden costs associated with it. Costs that can include configuration changes, training, backup/restore, and data protection etc.

In addition, there's risk. Reconfigurations are risky in that they can potentially impact reliability. DataONTAP 7G with FlexVols addresses all of the above issues plus some more.

DataONTAP 7G virtualizes volumes in Netapp and Non-Netapp storage systems (V-Series) by creating an abstraction layer that separates the physical relationship between volumes and disks. A good analogy I read from a Clipper Group report was comparing capacity allocated to FlexVols versus other traditional approaches, to a wireless phone versus a landline. While every phone has a unique number the wireless phone can be used anywhere, whereas the landline resides in a fixed location and can not be moved easily.

FlexVols are created on top of a large pool of disks called an Aaggregate. You can have more than one aggregate if you want. Flexvols are stripped across every disk in the aggregate and have their own attributes which are independent of each other. For example, they can have their own snapshot schedule or their own replication schedule. They can also be increased or decreased in size on the fly. They also have another very important attribute. Space that is allocated to flexvol but not used can be taken away, on the fly, and re-allocated to another flexvol that needs it. The Aggregate(s) can also be increased in size on the fly.

Flexvols can also be cloned using our FlexClone technology which I'll address another day. But just so everyone understands, a Flexclone represents a space efficient point-in-time copy (read/write) of the parent Flexvol but can also be turned into a fully independent Flexvol itself.

Another important aspect of the flexvols is size granularity. Starting with a size of 20MB up to 16TB it gives users the ability to manage data sets according to their size while at the same time, obtain the performance of hundreds of disks. Couple that with DataONTAP's FlexShare, Class of Service, we have a very elegant solution for application consolidation within the same aggregate. By deploying 7G the days of wasting drive capacity in order to obtain performance are gone.

Another very useful feature of 7G is the ability to do Thin Provisioning as well provide Automated Policy Space Management in order to address unforseen events that can be caused by sudden spikes in used capacity.

I'll be writing more on the last two subjects pretty soon so stay tuned

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