allocsize mount option

[Eric Sandeen]

Gim Leong Chin wrote:
> Hi Dave,
> 
> 
>> fragmented, it just means that that there are 19% more fragments 
>> than the ideal. In 4TB of data with 1GB sized files, that would
>> mean there are 4800 extents (average length ~800MB, which is 
>> excellent) instead of the perfect 4000 extents (@1GB each). Hence
>> you can see how misleading this "19% fragmentation" number can be
>> on an extent based filesystem...
> 
> There are many files that are 128 GB.
> 
> When I did the tests with dd on this computer, the 20 GB files had up
> to > 50 extents.

which is at least 400mb per extent, which is really not so bad.

-Eric