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InsaneJ
6th August 2017, 22:26
Dynmap for the TFC server has been causing us some issues for the past months. The issues are related to disk I/O. We keep all the Dynmap tiles on a separate 4TB WD Purple drive. Normally this should be more than fast enough. However for some reason we're seeing thousands of write IOPs being generated which that drive can't handle. As a rule of thumb a mechanical hard drive can do up to 100 IOPs.

We have formatted the WD Purple drive using Btrfs which supports "packing" iirc. This allows a file to only take up the size of the file instead of allocating partly empty sectors. You can see what not having a file system that does packing by opening the properties of your C:\Windows directory. You'll see that "Size on disk" is much larger than just "Size". Having millions of tiny .png files for Dynmap would normally take up a huge amount of space. Now it "only" takes up between 2 and 3TB. I can't check at the moment because, and this is the main reason I'm posting this, Sverf is now formatting the WD Purple drive using ReiserFS 4.

Because of this the TFC servers will be down for a little while. When they're up and running again Dynmap will be empty. We'll start generating the new tiles shortly. Generating tiles for all the TFC servers is going to take some time. Last time it took us a few weeks. We'll start with the FreebieTFC map first since that's used more than the others.

InsaneJ
7th August 2017, 20:17
Things are looking good. The Dynmap drive was configured as a pass-through disk in the raid controller. This seemed to caused the issue. I've removed the pass-through disk and created a regular raid 0 array with only 1 disk. Then added a new virtual disk to the server virtual machine. After that Sverf formatted the new drive as ReiserFS 4.

TFC Freebie Dynmap tiles are being generated as we speak and even now it feels a lot more snappy. Hooray us!