Take a Dip in the Flash Pool: NetApp’s Auto Tiering

With NetApp DataONTAP 8.1 going GA I can finally talk about Flash Pools. Flash Pools is a part of the Virtual Storage Tier (VST). VST is NetApp ‘s automated storage tiering. It’s a combination of Flash Cache and Flash Pools. The flash pools is what I have been waiting for. Lots of NetApp’s competitors including many startups have been pushing their auto-tiering technologies for a while. NetApp’s core features, including WAFL have keep them in the game but I tend to think some sales where lost when Flash Cache wasn’t enough. Flash Pools are differently going to change the reference architecture for FlexPods with the inclusion of DataONTAP 8.1.

Flash Pools are a combination of NetApp’s regular 80GB SSDs and hard disk drives. The SSD storage is RAID protected which allows the addition of caching of random write operations as well as random reads. If your using a Flash Pool with an aggregate and you have Flash Cache on your controller, the Flash Cache will be ignored. I think I would tend to lean towards just using the Flash Pools only because any HA fail over events on the controller cause the Flash Cache to be “warmed”. Flash Pools can provide more consistency which is a good thing in my books. I haven’t had time to look at the cost of only a Flash Pool approach but hopefully it’s cheaper. They’re going to be use cases for just accelerating reads but I prefer a uniform environment even if that’s pipe dream.

I really like the fact that Flash Pools is simple to setup and it’s being offered in the smaller model of NetApp Filers. Flash and SATA seems like a winning combo and should be able to push consolidation ratios. Here is small video on the setup for Flash Pools.

I am curious to see how the drive life of the SSD’s work out with the increased load and at what point the controllers won’t be able to handle the IO on NetApp’s lower end models. I guess time will tell.

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