Question


How can I customize CR's image using the overlay feature?


Environment


OnApp with CloudBoot compute resource


Answer


Overlay is an early boot feature that allows overlaying a CloudBoot image with any customized hardware drivers to be executed before the IS service is started.

Please note that this does not apply only to NIC drivers, though the NIC drivers have to load first to access the CP NFS resource. So, they are embedded in the CloudBoot RAMDisk image. All customization files are stored on the Control Panel server. You can find them using the following path:

/tftpboot/images/centos5/diskless/snapshot/<CR_mac_addr_dir>/overlay/
CODE

Example

/tftpboot/images/centos5/diskless/snapshot/90-e2-ba-73-8a-00/overlay/
CODE

All the tree structure after the <overlay> directory will be automatically copied to the CR's "/" upon the next reboot.

When moving out these files (because of the failures occurring when starting the IS daemons), test them by reapplying on one of the CRs, one by one, as long as they may contain important customization which is required for appropriate work of the storage network, benchmarks, etc. It will allow determining which files are problematic towards the IS functionality.

The Customizable CloudBoot Images page describes how to load drivers using the overlay feature.

Please note that some specified files/scripts, which had been applied through the overlay, may not work properly after the next update of the RAMDisk and even can lead to the system crash on booting.