[Gluster-users] Any workarounds for creating a non-empty replicated volume

[Andreas Hollaus]

Hi,

I understand that the proper way to create a GlusterFS volume is to use 
bricks that consists of empty directories. Are there no workarounds for 
this, so that a non-empty directory could be transformed into a 
replicated brick?

I have seen that when there are existing files in the directory before 
the volume is created, those files will be treated by GlusterFS when 
more data is written. For instance:

1. A file which exists on both replicated bricks will get additional 
data whenever written using the volume path.
2. A file which exists on only on of the bricks will be copied to the 
other brick and get additional data whenever more data is written using 
the volume path.
3 A file which exists on both replicated volumes, but with different 
contents, will get additional data whenever written using the volume 
path. However, the original differences will remain so the files are not 
properly synchronized.

However, I have failed to synchronize these files using stat. I have to 
write to the files to achieve these results. Could this or any other 
circumstance be used to create a replicated volume in a preoccupied 
directory?

Have there been any ideas to support such cases? I guess it wouldn't be 
impossible to detect this as those files that already exists in the 
directory lack the extended file attributes that are used to determine 
if the file is in sync. Whenever those attributes doesn't exist, the 
file could be copied to the other bricks (the favourite child option 
could be used to state which brick to trust). Maybe this is not the way 
GlusterFS is intended to work, but I guess it could have been 
implemented like that, right?

The reason I ask these (rather stupid) questions is that I am really 
worried about performance when we create our volume and have to move all 
files to the new directory.


Regards
Andreas