Re: Hybrid Storage proposal

["Matias Bjørling" <m@bjorling.me>]

On 02/20/2013 08:19 PM, Alex Elsayed wrote:
> Matias Bjorling wrote:
>
>> Here is a short proposal for the hybrid storage cache idea with
>> introduction/motivation and a bird's eye view of an approach to implement
>> a hybrid storage cache for btrfs. Please note that there is currently no
>> available patches. We would like to get as much input before as possible
>> before we start designing and implementing a solution.
>
> Just to toss this out there, aside from the option of 'cache chunks' there
> is the option of using normal chunks, and instead place extents on chunks
> based on performance characteristics of the underlying device.
>
> As an analogy, if the above proposal is closer to the 'bcache' approach of
> treating the SSD purely as a performance enhancer that does not contribute
> to capacity, performance-based allocation is closer to the 'btier' [1]
> approach in which the SSD does contribute to capacity, but has 'dibs' on
> performance-sensitive data.
>
> [1] Btier sourceforge page: http://sourceforge.net/projects/tier/
>
> Lessfs homepage, with btier info: http://www.lessfs.com/wordpress/

Good point. I think both approaches are relatively easy to combine.