Uploading ISO's to storage domains in oVirt

oVirt currently doesn't allow you to upload ISO's over its web interface - you'll need to use the cli to do this.

If you wish to upload an ISO to an ISO storage domain you should issue you should issue:

engine-iso-uploader --iso-domain <storage-domain-name> upload <path-to-iso>

[CENTOS] Displaying messages in the mail queue and manually flushing them

The mail queue can be checked with simply:

mailq

Alternatively if you are after a count of messages that have been deffered for what ever reason you can issue:

find /var/spool/postfix/deferred -type f | wc -l

and to attempt to resend them we can issue:

postqueue -f

Preventing kernel modules from being loaded at the bootloader / grub in CentOS 7 / RHEL

Although this will typically done with the mod probe there are situations where the need to disable specific kernel modules before loading the kernel are necessary. One such situation is while I was installing a fresh instance of CentOS on an older server.

At the CentOS bootloader select the relevant entry and hit tab. You should now be able to edit the Linux kernel (vmlinuz) boot parameters.

Simply append:

module_blacklist=<module_name>

and hit enter.

This should theoretically work on all modern kernels / distros - so is not just limited to CentOS / RHEL.

Source: https://www.kernel.org/doc/Documentation/admin-guide/kernel-parameters.txt