What happens to altbootbank after rollback and another update

[nponeccop]

I have a HP G7 server which has a pink screen with HP image of 6.5. I learned this a hard way by upgrading and pressing Ctrl-R after the crash to revert back to 6.0

Now vSphere Client (I have free ESXi) shows that I have 6.5 in altbootbank and 6.0 in the primary bank.

Now I want to apply another update, but want to be sure that I'll never be offered to "rollback" to the dreaded PSOD of 6.5.

So I basically want to back up my primary boot bank to altbootbank and then apply the patch. So I can rollback from patched 6.0 to current unpatched 6.0.

Is such backup of current config to altbootbank done automatically every time I update using esxcli or bootable ISO?

[virtualg_uk]

From the architecture documentation:

The ESXi system has two independent banks of memory, each of which stores a full system image, as a fail-safe for applying updates. When you upgrade the system, the new version is loaded into the inactive bank of memory, and the system is set to use the updated bank when it reboots. If any problem is detected during the boot process, the system automatically boots from the previously used bank of memory. You can also intervene manually at boot time to choose which image to use for that boot, so you can back out of an update if necessary.

https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/ESXi_architecture.pdf

Hope this helps

[nponeccop]

The article is still good to describe the architecture, but it's outdated in details. For example, the bootbank footprint is not 32 MBs but closer to 200 MBs now, and all types of non-image based updates are allowed now. So many details there are no longer apply - e.g. " the providers must be packaged with the system image, and cannot be installed at run time", as there are VIBs that don't require host reboots.

Also, it's not clear how the boot bank cloning is achieved. "When you upgrade the system, the new version is loaded into the inactive bank of memory" is not specific enough.

What if I install just one VIB? It seems if the VIB doesn't require reboot it's installed to the primary bank and the special --altbootbank esxcli option exists.

[virtualg_uk]

Yes a very valid point about the VIBs, my understanding is that an upgrade is an increase in the build number but I'll run this through my lab tomorrow unless someone can clarify beforehand?

[nponeccop]

It's strange that nobody knows how patching interacts with dual bootbanks. It's an important reliability consideration.

It seems that boot failure is not that common, and if you have a large farm you can test if upgrade is successful in advance in a lab. So nobody cares about having a working altbootbank because there's little need.

[virtualg_uk]

I've found a KB on this here:

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=10336...

Reverting an ESXi host is only valid if the host was updated using these methods:

• VIB installation or removal
• Profile installation or removal
• ESXi host update using VMware Update Manager
• Updated from a ISO

I will get this tested in the lab when I get some time!