Riz Khan on April 24th, 2010

On Virtouzzo VPSs you can calcualte the Guaranted, Buestable and other memory usage using below formulae :


Guaranteed memory = barrier of vmguarpages / 1024 * 4

Burstable memory = privvmpages / 1024 x 4

Current Memory Usage = physpages held value /1024 * 4

Current Usage (RAM + SWAP) = oomguarpages held value /1024 * 4

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Riz Khan on April 24th, 2010

We can find the IP delegation for any IP using below command , i.e. using this command we can find which Nameserves are responsible for this IP and e.g. should provide the Reverse DNS for that IP :


dig +trace -x 22.33.44.55


Where 22.33.44.55 is the IP for which we want to find the delegation, it can be any IP.

dig
Dig is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) which were queried.
Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than dig.

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We can check the Php versions and configurations like suphp, phpsuexec or dso on a Cpanel based servers on shell using below command :


/usr/local/cpanel/bin/rebuild_phpconf --current

Sample output :


root@myserver [~]# /usr/local/cpanel/bin/rebuild_phpconf --current
Available handlers:
suphp dso cgi none
DEFAULT PHP: 5
PHP4 SAPI: suphp
PHP5 SAPI: suphp
SUEXEC: enabled
root@myserver [~]#

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Riz Khan on April 24th, 2010

We can run certain processes like account packaging or account restores with certain cpuwatch value to make sure the server load remains in control and thus normal server operations continue to work during the cpu intensive restore or package processes. This can be achieved by using below command :


/usr/local/cpanel/bin/cpuwatch 10 /scripts/restorepkg USERNAME

We can keep cpuwatch to 10 , or lower or higher value depending on the specificiations of the server and our requirements. As accesptable load values depends on server specificiations specially the number of cores.

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Riz Khan on April 24th, 2010

The below Application Error is a common error for windows vpss (virtouzzo based ) :


Application Error
The server encountered an internal error or misconfiguration.
Contact your Hosting ProviderPlease report this problem to the technical support.

This is usually caused by VPS hitting its memory paramets , the QOS alerts can be checked from vzmc/pmc to confirm this.

A temporary solution would be restart the the vps to release the memory resorucse and for permenent solution make sure to check how frequent the QOS parameters are hitting their limit and what is causing this high usage and resolve that accordingly.

After restarting vps , make sure to check it in new browser windo

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If you delete a dns zone file for mistake in Cpanel/WHM and the account has lot of subdomains , then it can get very time consuming to fix this manually , by first adding the zone file and then adding entries for individual subdomains, below trick can fix this :

  • Rename the domain name from WHM to some other name temporairily , which will create the zone file with new name for main domain and will add zone entries for all subdomain as well.
  • Now rename the domain name again back to original , and here you go , with complete zone file back in action.

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