Re: Offline Deduplication for Btrfs

[Gordan Bobic <gordan@bobich.net>]

On 01/05/2011 09:14 PM, Diego Calleja wrote:
> In fact, there are cases where online dedup is clearly much worse. For
> example, cases where people suffer duplication, but it takes a lot of
> time (several months) to hit it. With online dedup, you need to enable
> it all the time to get deduplication, and the useless resource waste
> offsets the other advantages. With offline dedup, you only deduplicate
> when the system really needs it.

My point is that on a file server you don't need to worry about the CPU 
cost of deduplication because you'll run out of I/O long before you run 
out of CPU.

> And I can also imagine some unrealistic but theorically valid cases,
> like for example an embedded device that for some weird reason needs
> deduplication but doesn't want online dedup because it needs to save
> as much power as possible. But it can run an offline dedup when the
> batteries are charging.

That's _very_ theoretical.

> It's clear to me that if you really want a perfect deduplication
> solution you need both systems.

I'm not against having both. :)

Gordan