Running top for beer and profit
June 9, 2009,
Sometimes a small tweak in your system or your thought process can save you heaps and heaps of time, which you can spend otherwise, for more useful things.
At home I have a small eXcito Bubba NAS box that I share with a few people. I have put my MP3s (I also have the original CDs and records) and tons of pictures on it, which I collected from different machines and external harddisks (conveniently creating a single point of failure until I have proper backups for the pictures). The box itself is not that fast. Inside is some ARM CPU and when you do something like tar over ssh the CPU load increases quite a bit. Transferring 16 GB of data from a machine (so I can wipe delete the data to install Fedora 11) took a lot of time. After about 7 hours (and still going) I decided to log onto the machine and just see why it was taking so long.
After logging in on the NAS box and running the top command I saw a process called mediatomb which was eating quite a bit of CPU time and doing considerable disk I/O. Mediatomb is a UPnP media server and it was apparently trying to keep up with the new data being added and keep its database in sync. This caused quite a bit of delay, because both tar and mediatomb wanted to access the disk. Stopping mediatomb (no one here uses it anyway) lowered the load on the machine a lot and speeded up the process considerably. Once again it has been proven: it never hurts to investigate performance issues and often they can be fixed really quick.