On 11/10/2011 09:11 AM, David Sterba wrote:
On Wed, Nov 09, 2011 at 10:01:13AM +0900, dima wrote:
Just for the record - I could find a solution thanks to the btrfs wiki
being online again. In Gotchas it says
mount -o nodatacow also disables compression
and indeed it does. Remounting with this option and re-saving the file
makes it uncompressed. However, I could not find how to remount the
filesystem afterwards without nodatacow.
I saw this mentioned on irc today (that nodatacow diasables
compression). There is a way how to turn off compression on a file --
with help of the NOCOW _file_ attribute, ie. you don't have to remount.
* create the file, compression enabled
* set NOCOW (with the attached single-purpose nocow.c utility)
* btrfs fi defrag the_file
Make sure you have enough free space for the uncompressed file size. You
can compare the extent layout before and after the defrag with
"filefrag -v" .
Hello David,
Thank you, I will try it out tonight. Is there any way to see if nocow
attribute was set on a particular file, and is there any way to unset it?
thanks
~dima
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