CFD Online Discussion Forums

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-   -   Site loading slow (

praveen July 24, 2010 00:22

Site loading slow
Today I find cfd-online pages take a long time to load. I am in India. Its actually been slow for last 2-3 days if I remember correctly, but today is still slower.

pete July 24, 2010 04:15

Are all parts of the site slow or only some sections?

praveen July 24, 2010 04:29

I have checked forums and wiki, and they are slow. Hitting "Post Reply" to a message also takes a long time to load.

pete July 24, 2010 06:23

The server is not very highly loaded right now. A few days ago the server was under quite some stress due to a massive spam bot attack, but that bot is gone for now.

If CFD-Wiki and the Forums are the only sections that are slow it could perhaps be related to our database engine (MySQL), since those sections make heavy use of MySQL. I'm currently on a mobile connection so for me eveyrything is quite slow now. Is, for example, the links section quick for you or is that also quite slow? The links section is mainly plain HTML pages so if that is also slow it must be a problem which is not directly related to our server.

niklas July 26, 2010 09:06

The last days cfd online has become incredibly slow, every page takes about 1 min to load for me.

praveen July 26, 2010 09:20

It was very slow just a few minutes back. But now it seems to be fine.

pete July 26, 2010 22:19

We have changed some settings in our firewall just now. Apparently our web-host had imposed more strict hacking filters so that we automatically banned IP ranges that had computers that the filter indicated were trying to hack our server. We have relaxed the filters slightly now.

These firewall filters could be related to the slowness problems also. Is it better now?

praveen July 27, 2010 11:20

Its again slow and practically unusable. Slow both from my office and home, which are different ISPs.

jola July 27, 2010 18:33

We are examining the network problems. Right now it is also very very slow for me, and then 10 minutes later it is quick again. We do not know why and our ISP is helping us to diagnose the problem.

jola July 28, 2010 04:47

Two server problems
We have had two different problems with lately, one problem is related to our firewall and some unnecessary strict hacking filters and one problem is related to our Apache web-server installation and Apache stalling.

The firewall filters have caused automatic bans of IP ranges that we did not intend to ban. For example, a couple of universities have been banned automatically by our firewall because they have one student who has been trying his skills as a hacker... These filters have now been relaxed and we have received reports that the universities that got banned are now able to access CFD Online again.

The Apache web-server problems is what causes our site to become very very slow at times. We have not solved this problem yet. We can fix it temporarily by restarting Apache, but that is not a long-term solution. Hopefully we will soon find why Apache all of a sudden is breaking up for us.

We apologize for all these problems. These things always tend to happen when you are away on vacation :mad:

niklas July 28, 2010 07:33


Originally Posted by jola (Post 269093)
For example, a couple of universities have been banned automatically by our firewall because they have one student who has been trying his skills as a hacker...

we want names :)

now it is working properly again.

jola July 29, 2010 04:02

Server has been working well for 24hours now
Is anyone still having problems with being very very slow or delivering an incorrect frontpage (the Apache installation page)? If you do please post a quick reply here so that we know that the problem is not completely solved.

We have gone through our server installation with a fine comb and have fine-tuned several settings both on the Apache web-server and on several other tools that we use (DNS server, firewall, spam and hacking filters, mail-scanning, ...). We have not found anything that can explain why our web-server stalled and became virtually unusable earlier this week though. Now the web-server has been working well for 24 hours and we hope that all the things we changed will keep quick and healthy.

However, it is a bit irritating that we haven't found a single root cause of these problems. Hence, they might come back an hunt us again.

praveen July 29, 2010 04:07

Seems fine to me now. I dont feel any slowness at present.

pete July 30, 2010 04:53

Still working
Site seems to still be working well. Please contact us if anyone is still having problems. Yesterday we had a lot of traffic and easily served more than 3,000 web-pages per hour for a long period (see and the server was not even half-loaded.

sail March 6, 2011 20:18

hi. just want to report that the forum is getting really slow (has been few days)

it need around 1 minute to give me any page, even if ti contains just one message.

i'm in the uk and this happens with various isp.

pete March 7, 2011 04:00

I have also noticed the site being a bit slow over the last week. Not as slow as you mention, but slower than before. It is not related to the server being overloaded and it is not related to only http traffic. Most likely it is a network issue. I will send a question to our ISP to ask if he has any ideas what might be causing this. Anyone else who has also noticed this slowness over the last week?

I should also say that since around Christmas has been running with a throttled network speed. The reason is that our ISP was attacked by a hacker who managed to start up very aggressive IRC flood-bots. These bots crashed his entire network. Several servers were compromised and we think that the hosting environment our ISP runs has a security hole. While we are still running on this vulnerable hosting environment we will run with a throttled network speed. I do not think that this is what causes the slowness seen over the last week though. This mainly affects large file transfers.

We have started to move over to a completely new hosting environment. Soon we will be ready to move over the entire site to a completely reinstalled server with a new hosting environment. Then we will run full speed without any network throttling. If you want to follow the development on this please read our twitter page:

akidess March 8, 2011 05:57

I have noticed the slowdown in the last days as well. Right now it's slow but tolerable; earlier this morning pages from cfd-online would take minutes to load.

jola March 9, 2011 15:31

Our ISP has changed something in our network configuration. Is the site quicker now or is it still slow?

akidess March 9, 2011 17:20

It seems to be a lot quicker now!

sail March 9, 2011 22:03

definitely lot better!

well done.

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