load on cpanel server

[Guest]

Hi, Im new to CL.

We have an abusive account on one of our cpanel servers. Cloudlinux in general has controlled this account from crashing the server, however we dont seem to be able to bring down the load to what we would like. Id appreciate any advice.

Server is one of our VMware vms, 2 core, 4gb ram, 50 websites, mainly wordpress.

All users (apart from the one abuser) are set on unlimited and 200% speed, so they are unrestricted.
If we suspend the abuser, load is 0.2-0.6, nice and low.

Ive tried setting the abuser on 25% speed, 512mb ram, 10 entry processes, etc.
Also tried them on 100% speed, more ram etc. This website just eats whatever you give it, if you give it 200%, itll use it!

Load doesnt seem to shift much whether we set speed at 25% or 100%, infact it goes UP if we restrict the speed to much?!. It fluxuates around 1-1.5. You may think, thats ok, the server is 2 core. However, we think this abuser is pushing the load up from 0.5-0.6 to 1-1.5, even when they are restricted in speed.

I feel I may be missing something or confusing a setting? Shouldnt we be able to restrict speed etc and the load comes down?

The other thing I thought CL did was throttle based on average usage. EG, some sites may want to burst up to 200% CPU usage but generally are good sites. The way CL works is it caps them even if the server is in a quiet period or resources are available.

[bogdan.sh]

Hi,

CloudLInux is designed to keep websites stable, and limiting CPU normally has virtually no overhead. Yet, if you set limits to low -- you will increase amount of context switching (switching between which process gets executed), that causes overhead (to accommodate the switch). This can easily increase LA, and show up as increased %sys in top header, meaning kernel is busy switching context doing his limiting job. This is just how task switching works and this is why recommend setting SPEED to 100% as minimum amount.

Yes, CPU burst is not implemented and there were only few votes about it:https://cloudlinux.uservoice.com/for...-when-spare-cp

[sguk07]

Hi Bogdan,
Thanks for your reply. Thats understandable and I can appreciate what you are saying.
Cloudlinux does a good job of keeping things stable over the longer term and allocating 100% CPU (50% of the server) to each account is based on them only using this in bursts, such as updates, Wordpress ajax, uploads etc or a sudden burst of traffic. This is great as it stops them taking over the whole server and normally their usage drops to average levels of 10-20% CPU.

If we set the CPU limit to 100% on this particular website they immediately start using 100% and they continually use it. Effectively they are using 50% of the server all the time when the other 50+ customers use much less!
Customers will not move to a VPS if they believe the website is ok (even if it shows its hitting the limits in Cpanel), however they might if its really slow.

They seems to stick within the default limits for the other settings inc memory 1024. Hard to know how to deal with them, so keeping CPU low and a slow website may be the only way to ensure their usage is kept fair.

Thanks

[bogdan.sh]

It sounds like you need more powerfull server to handle all requests. Yes it is a balance game, how to provide enough resources over LVE limits to have fast customers websites but same time how to keep server stable. I also believe you should not fight the load itself, load average 1.5 on two core server is acceptable.

Try optimizing server, tune mysql, try using another PHP engine (mod_lsapi) etc.

[sguk07]

I will take a look at mod_isap.
We already have a powerful host, ssd array etc, this is a vps on that host. As I said before, without this one account it hardly sweats.
I have to disagree with your suggestion to throw more resources at this to balance it. This is about fairness, one account, paying a fraction of the server cost does not warrant more resources.
We tried Cloudlinus for this very reason, it has worked to stabilise things, I will assess the other benefits. Thank you for your time.