Synology vagueries: slow transfers, 100% volume util, very high load average, very high IOWAIT

I've been a very happy user of Synology systems for quite a few years now. The past few weeks I've ran into quite some performance issues though, so I decided to get to the bottom of it.

Symptoms:

• CPU usage is low, with <15% active usage.


• CPU usage is stuck on 70-85% IOWAIT.


• My load average is very high, at 14.xx consistently.


• The performance monitoring tool shows 100% volume utilization.


• Very low transfer speeds to/from the NAS.


• Very long connection times on the file shares.


• Very slow logins and bad response times on SSH and the web interface.

I have undertaken a few steps that seem to have gotten me in the right direction...

1. I have gone over the list of active services and disabled the ones I do not use.


2. I verified the installed packages and I've removed all the things I really don't need.


3. I have disabled the Universal Search function, which cannot be disabled without trickery (see below).


4. I have disabled the Indexing daemon in full, which also cannot be disabled without extra effort (also below).

In order to disable Universal Search:

1. Login through SSH


2. cd /var/packages/SynoFinder


3. sudo cp INFO INFO.orig


4. sudo vi INFO

Make the following changes:

ctl_stop="yes"
ctl_uninstall="yes"

You can now restart Package Center in the GUI, browse to Universal Search / SynoFinder and stop the service. You could even uninstall it if you like.

In order to disable the Indexer daemon:

1. Login through SSH


2. sudo synoservice --hard-stop synoindexd


3. sudo synoservice --disable synoindexd

The second step is needed to also stop and disable the synomkthumb and synomkflvd services, which rely upon the synoindexd.

One reboot later and things have quieted down. I'll keep an eye on things the next few days.