Date Changes on XenServer VMs

If you've ever tried to run 'date -s' on a virtual machine running on a XenServer host, you'll have no doubt noticed that it returns the right date, only to be back to it's previous setting the second after. This has to do with the kernel level date sync between the XenServer Host and it's Virtual Machines. While this is very handy as it means that all servers have their date set by the hardware node without having to run ntp in all of the virtual machines in your setup (though running ntp between XenServer Hosts in a pool is recommended), it means you can't update a single vm's date to something other than that of the XenServer Host. Luckily, this is simple to fix!

To allow a single VM to have a unique clock, log into that VM and run:

echo 1 > /proc/sys/xen/independent_wallclock

And to change it back:

echo 0 > /proc/sys/xen/independent_wallclock

I've tested this on Citrix XenServer 5.5 and 5.6. If you're going to leave it like this for any decent length of time, I'd Highly recommend setting up an NTP client on the VM to keep thing's synced somewhere. If it's a completely weird time setting, yet based on real time, you can always have a script on a host with NTP run an ssh command hourly to set the time based on your offset.

Installing New Fonts in Gnome 3.x

I found a few suggestions on how to do this online. Browsing to fonts with Nautilus and adding plugins to the system config pages and I really just want to say that's all overkill. This is what I found; it's REALLY easy to add fonts to Gnome 3.

1. Open up a terminal, see if you have a ~/.fonts/ dir. If you don't make one.
2. Copy new fonts into this directory.
3. Congrats, you're done. Open a beer and assign some new fonts to things.

So far I've found .otf and .ttf fonts work well. .svg, .eot, and .woff don't, but there may be additional packages to make them work. So far I haven't needed to as most fonts seem to be found in the .ttf format anyway.

As a side note, I've found a lot of 100% free to use fonts (even commercially) at http://www.fontsquirrel.com I'm sure there are some other great sites out there too, but this one should get you started on your journey into font nirvana.

PHP 5.3 in Centos 5.x

So, CentOS doesn't come with php 5.3. I know what you're thinking "But there are rpms for it, I can see them listed in yum!" Okay, true, if you do a "yum search php53" you'll get back a list of php 5.3.x packages. But try to find something like memcache or mssql in there? Not there. However, IUS has the rpms you've been waiting for. All you need to do is (for x64 CentOS):

wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/ius-release-1.0-8.ius.el5.noarch.rpm

wget http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/epel-release-5-4.noarch.rpm

rpm -ivh epel-release-* ius-release-*

Hint: if you get a 404 on these links, open http://dl.iuscommunity.org/pub/ius/stable/Redhat/5/x86_64/ in a browser, find the 'ius-release' and 'epel-release' files and substitute them for these.

You'll then have the IUS repo installed so you can simply "yum install php53u". For me, this consisted of a list of php53u-??? files. If you want it all, yum is nice enough to oblige by running "yum install php53u-*".

It is important to note that these files do not necessarily obsolete CentOS Stock packages. You will most likely have to run "yum erase php" before you install the new php53u packages or risk overlap/inconsistency.

I know this isn't that much of a trick to accomplish, but I just had to do this and I wanted to write it down for myself since I have to do it on a number of hosts... Figured I'd share it here.

Welcome

I'm hoping to make this a technical blog about random issues I come across during my various technology related endeavors. I'm not sure if it will be useful to many people, or to me in the long run... I'm hoping, however, that not only will it be a good way to keep track of problems and solutions I come across, but a good way to share that with people other than myself who are, perhaps, running into similar difficulties. I may from time to time post an interesting link or an op-ed piece if I have time and/or a reason for such things. Thanks for reading!