Is transparent compression available with the filesystem that unraid uses? I have a lot of data that compresses VERY well (19:1) and would rather have it compressed than buy more disk....

It is not available, and it's not even on the Roadmap anywhere, as far as I know.  Something like this though seems better handled by any of the many archiving or backup or sync programs out there.  For example, I use SyncBackSE to backup whole trees with compression to unRAID.  I'm sure some aspects of it could be done faster natively on the unRAID server itself, but once you start down that road, you will also hear requests for encryption and synchronization, etc, and there are a number of programs that already handle all of the configuration and dialoging necessary.

 

It doesn't mean that you can't request advancements like this for the future though.  Tom does listen to what people are asking for.

I'm a big user of SyncBack... I think I'll just work on some scripts that compress certain directories on my unraid box. It's mostly Photoshop Lightroom backups... All are about 20mb... compress down to 1.1mb...

This isn't very seamless but if you can isolate that data, and don't mind tinkering you could have a look at something like :

 

http://miio.net/wordpress/projects/fusecompress/

 

No idea if it will build under unraid easily or not, but the fuse subsystem is all there waiting if it does...

I would like to see LessFS working in unraid.  Compression and deduplication -- very good for backups.

 

The main issue that would need to be worked around is that LessFS currently uses a single file for storing data blocks (and separate databases for meta data, etc.).  It would be better if LessFS could have multiple files for data blocks, (one for each data drive in your unraid array), and could distribute the blocks between the files -- otherwise, you would need to find a way to have the single file span the multiple drives.