I’ve had a Synology NAS (an old DS107+, one of the earliest models) for several years now, and I love it for its simplicity of use and low energy/noise footprint as a home file/media server. I also like the fact that Synology does a pretty good job, for the most part, of keeping the software up to date and introducing nice new features.
However, when I upgraded my unit to version 3.1 of their Disk Station Manager (DSM) last week, I found that they had added a very undesirable “feature” which generates large thumbnail images for anything in your photo directory, apparently for use with the iPad app. Since I neither have an iPad nor have even enabled the PhotoStation component of the DSM software (which provides for a hosted web photo gallery–no thanks, I’m fine with Picasa web albums), I just wanted to turn this off. Furthermore, I found within a couple days of installing the update that the thumbnail generation process was constantly churning the disk and running the CPU at 100%, to the degree that normal file serving operations ran poorly. With the thumbnail process running, the unit could no longer even keep up with simple operations such as watching a video from the server over the normal Samba shares.
To my dismay, there is no option in the extensive DSM user interface to turn off this feature. I remember being slightly annoyed at this in previous versions, but it only made the system unusable once they added the XL thumbnails for the iPad app. (I have an nightly script that backs up my photo library to an offsite host via rsync every night, and I’d written it to ignore the @eaDir directories where the thumbnails are stored.) The synology forums seemed to be full of a lot of confused people trying to figure out how to turn off the thumbnail generation, but I was eventually able to identify the two key parts of the system that affect this.
If you want to simply disable XL thumbnail generation and leave everything else as-is, the file to edit is /usr/syno/etc.defaults/thumb.conf. You need to edit this file to remove the block starting with [thumb 1280]:
Note that there’s also a /usr/syno/etc/thumb.conf, but on my system it didn’t have an XL thumbnail block so apparently the file in etc.defaults was overriding it. (BTW if you need help getting an ssh session into your box and editing files, there’s lots of help for that on the Synology site. I logged in as root and used vi.)
The thumb.conf file is read by a thumbnail generation daemon (service) that is started through /usr/syno/etc/rc.d/S77synomkthumbd.sh. So after editing the thumb.conf file you can either restart your system, or just restart this service:
Once I did this, I no longer had “convert” processes at the top of my process list churning the hard drive and maxing out the CPU.
Alternatively, it sounds like you can also just prevent the thumbnail daemon from running at all on system startup. The rc scripts work a little differently from other *nix systems that I’ve used (although it’s been awhile); renaming the file didn’t appear to prevent it from starting when I tried that. The Synology wiki recommends adding a premature “exit” line right after the initial #!/bin/sh as a means of preventing a service from starting automatically (or ever, actually). I may go ahead and deactivate the process at some point but for now I was just satisfied that the XL thumbnails weren’t being generated.
In closing: Hey, Synology! Nice idea about the iPad gallery, but how about making it an option, once that’s not on by default, and with the warning that it will make older units practically unusable for their main purpose if activated?! I figured it out, but I’ve got some experience with *nix systems and the command line. I can see how a normal consumer user could be left completely helpless trying to address this problem and most likely end up blaming it on a (nonexistent) hardware fault.