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I have a Linux (CentOS 5.6) VPS which I use for hosting a few unimportant projects, but am currently really struggling with the performance. What can I do to find out if the problem is my configuration, or my host overloading the server I'm on?

If I ping the server right now:

Ping statistics for x.x.x.x:
  Packets: Sent = 100, Received = 73, Lost = 27 (27% loss),
Approximate round trip times in milli-seconds:
  Minimum = 161ms, Maximum = 207ms, Average = 167ms

The websites on the server are very very slow to load. I can connect via SSH, but there is a 2-20 second lag between me pressing the keyboard and anything appearing on screen.

Load is low (0.18 (1 min) 0.15 (5 mins) 0.09 (15 mins)), memory usage is low, the network interface is hardly being used... I've included some further information below.

# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
0  0      0 728372      0      0    0    0   161   252    0 1440 11  0 89  0  0


# free
             total       used       free     shared    buffers     cached
Mem:       1048576     320208     728368          0          0          0
-/+ buffers/cache:     320208     728368
Swap:            0          0          0

iftop shows me as the only thing with a connection open to the server.

Is there anything else to look at, or should I get in contact with my VPS provider?

Caleb
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Dan
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  • This looks suspiciously like the kinds of things I was experiencing on a regular basis on my previous VPS provider. Their support was no help at all. I finally changed providers, and haven't had any problems since (despite the new VPS living in a datacenter in the same city as the old one!). – Kromey May 12 '11 at 21:49
  • Hmm, interesting! Do you mind specifying which provider you were with? – Dan May 12 '11 at 21:50
  • I was with GoDaddy. Still get my domains from them, but I now have a Linode VPS, and I couldn't be happier with it (well, unless it was free, of course...). – Kromey May 12 '11 at 21:53
  • Ahh, well I'm not with them! Have heard good things about Linode, but are a little out of my price range. Have submitted a support ticket requesting to be moved to a quieter node. – Dan May 12 '11 at 22:16
  • can you tell us which services are you running there? I guess you're running apache.. but *sql? are all those thing with the default config? – boris quiroz May 13 '11 at 00:20
  • All the standard web services: apache, BIND, Postfix, Dovecot, ProFTPd, SSH, MySQL. All installed and managed via Virtualmin. Having spoken to my host, it appears their network was suffering a DDOS last night: would have been good to have been notified about this, but it does account for things really going downhill then. I think the residual slowness is probably a combination of geography, and me paying $4 a month! Thanks for all the help. – Dan May 13 '11 at 09:23

2 Answers2

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Your stats in general look sane. The only worrying thing are connectivity issues (RTT - depending on how far you are it may look acceptable - and especially packet loss).

To start with, try switching all services down and test your connection to the server with repeated ping and traceroute. It can be that you're having issues with your end of the link (ISP), the data centre has some problems or both.

Only after having coped with those issues should you start looking for other possible causes.

Karol J. Piczak
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  • The dropped packets seem to have resolved with a bit of time, though things are still going more slowly than I'd expect. The RTT isn't worrying me *too* much: I'm in the UK and the server is in the US. I was having no problems with my local connectivity when the issues were at their worst. Thanks for the help! – Dan May 12 '11 at 21:35
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I would get in contact with your VPS provider. If nothing else to get them working on the problem simultaneously as yourself to resolve it faster.

How is your connection at the client you are trying to connect from?

The stats you provided look OK. Most VPS's use shared hosts so it likely another virtual server on your host is having issues. Its also possible another server on your node is being DDOS'd - affecting your bandwidth.

Tyler Miranda
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  • I'm on a 50Mbit cable connection here which is fast and stable. The server is a cheap VPS, so I guess the node being overloaded is a plausible explanation. Thanks for the help! – Dan May 12 '11 at 21:30
  • Who are you using? I use a cheap VPS as well through a company called Webexxpurts. Its $15/month from 50GB of HDD 1.5GB of RAM and 1500GB/month of bandwidth. Ive been using for about 3 months now and have had zero problems. Speed has always been great. – Tyler Miranda May 13 '11 at 13:34