How to Fix 100% CPU Usage on Synology Diskstation NAS

I’ve been tweaking little things here and there with my Synology Diskstation DS 409 NAS server, more recently expanding its storage without upgrading the entire array (read about it here).  One of the things I finally did was upgrade from DSM (Diskstation Manager) 2.2 to DSM 3.0, which adds a completely new interface and fixes many UPNP issues I was having with my Patriot Box Office (read the preview).

There are so many new features to DSM 3.0 that you really owe it to yourself to explore every icon.  The sleek interface uses so much AJAX to the point that it runs virtually like a PC desktop, all within a web browser.  One of the things I came across while exploring the Resource Monitor was that my NAS’s CPU usage was constantly at 100%.  The 1GHz processor has a lot to do since it runs so many services and even calculates RAID parity in software, but there was no way that it should be pegged that much.  Because the CPU was constantly used, the NAS would not enter into any power-saving modes when not in use.

CPU usage back down to 5% after implementing this fix.  Notice how ‘convert’ is no longer in the list

After futher investigation I discovered what was causing the problem, and how to resolve it.   I clicked on the CPU graph to open up a sub-window that contained information about all the running processes.  You can also get CPU usage statistics from a terminal window (read how here).  It appeared that the “convert” command was using up 99% of the CPU’s time.  The “convert” command is used in Linux to convert photos between formats.

Location of the Photo Station applet in Control Panel

It appears that the Diskstation is creating thumbnails of my photos in the system-created “photo” share for use in its Photo Station application.  I had let the system run for several weeks, and the convert application was still chugging away on my meager 150GB of photos.  Since I don’t use this application, I opened up the DSM Control Panel and clicked on the Photo Station and disabled it.  This did not affect CPU usage, even after a hard reboot.

Even disabling Photo Station did not prevent convert from running

On the next page I show you how I fixed it…

After more investigation, it appears that this is a known issue with DSM 3.0 (as of 3.0-1337).   Any files in the default “photo” share will cause the NAS to automatically process them, resulting in the “convert” gobbling up all of the CPU.  I created a “photo” directory in the “public” share and moved the files (using the Linux “mv” command moved all of my photo files instantly, other than the hours it would have taken to move them via the network). I used PuTTY to login as root and move the files via the command line.

Make sure to enable SSH access before trying to use a terminal emulator like PuTTY

In order to prevent any accidental photo deposits in this “photo” share (thus starting this problem all over again), I hid the “photo” share from “My Network Places”. This is easy to do: just click on Control Panel, then Shared Folder.  Select the Photo share and click the Edit button.  You can then choose to hide this share from any Windows computer that browses the available shares on your NAS.

Hide the system-created “photo” share from the Control Panel

After implementing this fix, CPU usage went down dramatically and hovered around 5 to 10 percent.  I didn’t notice any substantial network throughput improvements, but Hard Drive Hibernation mode now works, and the NAS uses less electricity, which also translates into less heat.

It’s a shame that this bug exists, because it forces users to choose between a compromised NAS or a nifty media application.  Hopefully Synology will fix this in future updates, but as it stands I no longer use the default photo share.