[Ocfs2-users] where can i find shared-du and shared-filefrag ?

[Lentes, Bernd]

----- Am 15. Aug 2019 um 20:26 schrieb herbert van den bergh herbert.van.den.bergh at oracle.com:

>>
>> Some more questions:
>> The reflink (greensql.raw.snap) does not change, that means it's like a snapshot
>> ?
> That's correct. Any change to an extent shared by the original file and
> the reflink will cause a copy to be made of the extent. The file which
> was changed will get the new modified extent, the other file keeps the
> original extent.
>> But if i delete the reflinked file (greensql.raw) my snapshot is lost because it
>> shares extents ?
> No, the reflink still contains all extents, both the ones that used to
> be shared and the ones that are unique to the reflinked file.
>> If i delete the reflink, nothing happens beside that my snapshot is gone ?
> Correct, except that extents that were modified since the reflink was
> created which are no longer shared will be freed.
>> That means i can delete it easily if i don't need it any longer ?
> Yes.
>> And if i need the current file i just use the reflinked file, i don't have to do
>> s.th like merging oder blockcommitting ?
> 
> I'm not sure what you're asking. If an application continues to
> read/write the original file, then it will be the "current" file, it has
> the most up to date data. The reflink will have the data as of the time
> it was created. So if you need the "old" version of the file from the
> time the snapshot was created, you use the reflink. If you need the
> "new" version of the file, you use the original. Think of the reflink as
> a backup which is still sharing extents that haven't been modified yet
> with the original.
> 

Hi Herbert,

i think i got it.

Thanks.

Bernd
 

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