ESXi 5.5 Update 2 build 2143827 break Citrix NetScaler

If you happen to run NetScaler and upgrade to build 2143827 of vSphere 5.5 you will run in very nasty issues.

Specifically, your NetScaler will go bonkers if you enter in the management web interface or even via SSH; in general all things that start a network increase in term of traffic directed to the NetScaler will make it crash.

When it doesn’t crash you will still experience network communication drops, hangs, connectivity issues and such and in a very random fashion too (just to add some fun).

Fortunately VMware gave us a workaround.

To work around this issue, add the line hw.em.txd=512 in loader.conf file.

To add the line hw.em.txd=512 in loader.conf file:

1. Log in to the Citrix NetScaler virtual machine appliance as root
2. Locate the loader.conf file on the Netscaler virtual machine appliance by running this command:find / -name loader.conf

Note: There are two loader.conf files. The two files are ./flash/boot/defaults/loader.conf and ./flash/boot/loader.conf.
Modify the first one and ensure to take a backup of the file prior to making the changes.

1. Add this line in the loader.conf filehw.em.txd=512
2. Save the changes
3. Restart the NetScaler virtual machine appliance

For deeper details about the issue read KB VMware KB 2092809