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My VPS started to have random stints of high load (around 2-3, but the system becomes extremely slow, running ls takes like 30 seconds). I hadn’t changed anything on it, there was pretty much nothing but a Shadowsocks server running on it (with less than 15 users), the CPU usage percentage was consistently low (around 10), there was almost no IO usage, and the processes having the most TIME on CPU were mostly Ubuntu’s system processes. This problem has persisted for some weeks now, and there is no pattern to when the load gets high. Can this be a problem not with my VPS, but with the host it is on (the seller, that is)?

HappyFace
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2 Answers2

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It can. You can track IOWAIT and 'steal CPU' with htop (when you enable detailed stats), or track it with a tool like Munin.

This is how you enable the detailed stats in htop:

htop

And this is a Munin example of a somewhat overloaded backup server, causing a lot of IOWAIT:

Munin

How to set up Munin is described well on the net.

Halfgaar
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  • Can you be more detailed? How do I enable the detailed stats? What IOWAIT and steal cpu value ranges are problematic? – HappyFace Nov 15 '18 at 10:12
  • He sort of can not - this is not "help me learning", this is a place for professionals as per site rules. IOWAIT etc. are basic. – TomTom Nov 15 '18 at 10:34
  • @TomTom I am not ordering him. Of course he is free not to be more detailed. I am asking if he would be kind enough to be more detailed. – HappyFace Nov 15 '18 at 10:55
  • @HappyFace I added some pictures, but that's really only a starting point. You'll have to research how to set up Munin, read the figures, etc. – Halfgaar Nov 15 '18 at 11:04
  • I opened a new question after checking the results: https://serverfault.com/q/940160/471496 – HappyFace Nov 15 '18 at 11:43
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It can.

Resources on physical hardware are not unlimited. If other actors use up all the resources, then a seemingly low load can suddenly explode.

This is not specific to VPS - the same can happen on any shared resource, like LAN, storage. SAN are particular nasty on that - someone else makes a backup, all your IO is gone.

TomTom
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