Hi Hungwen,

To eliminate potential misunderstanding, could you tell me what you mean by “out-of-band” and “in-band” in relation to upgrades? Just to confirm that we are on the same page from the beginning.

Sorry, my poor English description makes you confused. For example, for Lenovo system, some firmwares can be updated via XCC GUI web. That’s an independent path via BMC. I think LCM should be the same method to do upgrade, but i don’t understand what kind of upgrade path it is. 

Lenovo XCC GUI

https://lenovopress.com/lp0880-xcc-support-on-thinksystem-servers

Ah, I see now what you mean! I thought you meant management path but wanted to double check. Thank you for explaining.

I have read the URL you included, thank you. While I did not see a direct indication of out-of-band upgrades capability, I trust that you it well.

I think the main difference to point out is that the Lenovo XCC is an integrated service processor while LCM is part of AOS software.

Software downloads are performed by Prism essentially but triggered by the LCM component of it.

When applying the software update, the non-impacting updates are placed at the top of the queue while the those that require workloads migration and reboot are placed at the end of the queue i.e. executed last (with all other dependencies considered, of course, such as BMC before BIOS and such).

Is that the information you were looking for? Does that answer your question?

So how does LCM connect to the target devices and execute firmware update on the target devices? 

https://portal.nutanix.com/page/documents/kbs/details?targetId=kA0600000008T3jCAE

The article says BMC has both an Ethernet interface and a directly attached interface to the chip-set. The ethernet protocol interface is inband connection and a direct attached interface(an independent interface) is out-of-band connection. 

So what kind of interface does LCM use to do the upgrade thing?

The BMC, BIOS and firmware upgrades are performed in-band but I have to explain how.

LCM places Phoenix OS image (a customized Linux OS) on the host and boots the host into it on the reboot. From Phoenix OS BMC, BIOS and firmware upgrades are performed leveraging OS utilities.

The process is outlined here Life Cycle Manager Guide: Effects of Updates on the Cluster.