
I came ...
And i don't have yet lay my unworthy hands on this object of desire ... tomorrow ... yes tomorrow ...
13 publicly visible posts • joined 15 May 2009
Dedup does not mean that you will have ONLY have one copy of your data at storage level but at file level which is quite different. If you have redundancy at storage level (mirror, raidz[123]) you will of course have redundant copies of data.
If you have a mirror configuration (without dedup) storing 2 identical files will lead to 4 copies of each block (2 for each file and 2X due to mirror). If dedup is "on" you will still have 2 copies of each data (due to mirror) but files will share identical mirrored blocks.
So yes it makes sens but you have to understand how it works.