I have HP custom ESXi 5.5 Update (HP-ESXi-5.5.0-Update2-iso-5.77.31017350310) installed in 2 servers and I'd like to update them to latest version, can I use update manager to reach this scope? How can I set it to do this job?
Yes,It is a easy way to patch your ESXi host with latest version.
Please check the documentation(third party) before you are applying in your environment.
VMware KB: Installing vSphere Update Manager 5.5 on a Microsoft Windows platform
This should help you. When you are uploading a baseline, choose the custom ISO instead of the actual ISO.
I would like to point out that using VUM to update will not actually update the drivers. I have been doing VMware for quite some time now and was not aware of this until recently. If you want your NIC/FC drivers to update afterwards you need to create a new baseline just for that.
You can update your NIC/FC Drivers using Update Manager or via commandline.
Here is a how-to using Update Manager: How to – Install VMware ESXi 5.5 Driver for Broadcom NetXtreme II Network/iSCSI/FCoE using Update Ma...