Posts Tagged ‘RHEL’

Twitter integration not working in WHMCS

Wednesday, May 14th, 2014

If you’re having problems with WHMCS’s Twitter integration feature on a CentOS/RHEL server, then chances are that you need to install the php-xml RPM.

The Twitter integration in WHMCS uses jQuery to make a POST request to announcements.php detailing the number of tweets to retrieve. This then in turn connects to the Twitter API, parses the response and returns it to the browser as HTML.

Something in this script requires one of the extensions provided by the php-xml RPM (dom, wddx, xmlreader, xmlwriter and xsl). If the module isn’t present, then the script fails silently and returns no tweets. You still get some HTML though – the Twitter icon, a single hyphen and the “Follow us on Twitter” button.

SolusVM displaying wrong disk usage statistics for Xen PV VMs

Sunday, December 29th, 2013

Recently some of our Xen PV VMs started to show strange disk space usage statistics in SolusVM – despite there being plenty of space left on the disk in the VM, SolusVM was reporting that the disk was nearly full!

I struggled to find any public information about this, but apparently it is a known problem with SolusVM and the version of the “df” utility used in RHEL/CentOS 6.5. There have been some slight changes to the way that df displays its output and this causes SolusVM to interpret the disk usage figures incorrectly.

SolusLabs have posted a workaround for this at http://bin.soluslabs.com/1083/38662948/raw/ and I’m reproducing it here for posterity as well as in the hope that it will get indexed:

Fix for Xen PV disk usage showing 100% when using a CentOS 6.5 host node
========================================================

The “df” output in CentOS 6.5 has changed. You may notice this when you upgrade you’re host node from CentOS 6.4. All the Xen PV virtual servers will show 100% disk space used.

On the affected host node edit /usr/local/solusvm/data/advanced.conf and add the following line:

XENFIXCENTOS6DF=”1″

Then run these commands:

wget https://www.dropbox.com/s/j8nu3ye09x9ehwq/command.php -O /usr/local/solusvm/www/command.php
wget https://www.dropbox.com/s/93hsnzzmpwny3r4/solusvmc-xen -O /usr/local/solusvm/core/solusvmc-xen
chmod 6777 /usr/local/solusvm/core/solusvmc-xen

Now when you reboot a virtual server (with the reboot button) the disk usage should update correctly.

Dell DSET on CentOS

Wednesday, September 11th, 2013

Those of you unfortunate enough to have encountered the Dell technical suport department will know their love for the Dell diagnostic tools. Those of you who run CentOS and have been asked for a DSET report (Dell System E-Support Tool) will also know that the DSET tool refuses to run on an “unsupported” operating system.

Luckily, DSET is quite easy to trick – just add the following to the top of /etc/issue (assuming that you’re running CentOS 6):

Red Hat Enterprise Linux Server release 6 x86_64

Now DSET will work as normal, blissfully unaware that it is running on CentOS and not RHEL. Remember to take the line back out again once you’ve finished with DSET.

Intel VT Virtualisation Technology on Dell PowerEdge servers

Saturday, June 19th, 2010

Somewhat annoyingly, Dell seem to like to disable Intel’s VT (Virtualisation Technology, sometimes called VMX) in the BIOS on their Dell PowerEdge servers, which means that you can’t use the Xen hypervisor to virtualise Microsoft Windows Server without changing this setting, which requires a reboot of the server to take effect.
You can use omreport from the Dell OpenManage Server Administrator software to check whether or not you have Intel Virtualisation Technology enabled.
If you haven’t got OpenManaged Server Administrator installed, then you can enable the Dell yum repository for CentOS/Red Hat systems and install it with:

wget -q -O – http://linux.dell.com/repo/hardware/latest/bootstrap.cgi | bash
yum -y install srvadmin-base
/opt/dell/srvadmin/sbin/srvadmin-services.sh start

Once you’ve got the Dell OpenManage Server Administrator services running, you can take a look at what processor is installed in your system and what the current BIOS settings are with:

omreport chassis processors
omreport chassis biossetup

The two attributes that you’re looking for are Processor Virtualization Technology (which needs to be enabled) and Demand-Based Power Management (which needs to be disabled).

If you need to change them, then you can do this with:

omconfig chassis biossetup attribute=cpuvt setting=enabled
omconfig chassis biossetup attribute=dbs setting=disabled
omreport chassis biossetup again and then once you’ve rebooted the server you can start taking advantage of the hardware virtualisation provided by Intel’s Virtualisation Technology.