vSphere 5.1 client not compatible with ESXi 5.0?

I recently upgraded one of my ESXi hosts from version 5.0 to 5.1. The upgrade of ESXi itself went fine (simply boot from the ESXi 5.1 install CD and select the existing ESXi 5.0 installation as the target and it gives you the option to perform an upgrade rather than a fresh install), but trying to access this subsequently with my existing vSphere 5.0 client install resulted in a message informing me certain components had to be downloaded. When I looked at what it was wanting to download it turned out to be the vSphere 5.1 client installer which I could sort of understand, so I proceeded with the upgrade of the vSphere client. Once the vSphere 5.1 client had installed I was then able to access the ESXi 5.1 host.

However, when I then tried to access one of my other ESXi 5.0 hosts the vSphere 5.1 client gave me the same message as previously and asking if I wanted to download new components. Looking at what it was downloading this time it turned out to be the vSphere 5.0 client installer! This suggests – and I couldn’t find it documented anywhere online – that the vSphere 5.1 client is not backwardly compatible with earlier ESXi hosts, which seems a bit dumb to me.

So, if you are upgrading an ESXi host from 5.0 to 5.1 and want to be able to able to manage all your ESXi hosts with the same vSphere 5.1 client, you will need to upgrade them all to ESXi 5.1.

RAID on my HP ML115 G5 ESXi server

Continuing with my exploits at rebuilding my HP ML115 G5 based home server running ESXi 5 I’ve now turned my attention to data resilience by looking at a hardware RAID solution.

After a bit of research I decided on using an HP Smart Array P400 Controller as it seems to be a good balance between performance and cost, particularly when coupled with the optional 512MB battery backed accelerator cache. Another reason for choosing the P400 controller is that it appears on the VMWare ESXi Hardware Compatibilty List.

There are lots on eBay for a reasonable price, many of which appear to be pulled from decommissioned enterprise rack servers. I got mine for £60 including the 512MB cache and battery.

The P400 features 8 channels split across two SFF8484 connectors. Typically these are connected to hot swap SAS drive cages but they can also be connected directly to attached SATA drives using an SFF8484 to SATA breakout cable, such as this one sold by Startech.

I’ve never used a hardware RAID solution before so it’s a new learning experience for me. The process involves using the HP Array Configuration Utility (ACU) – which can be booted from CD/DVD or USB flash drive – to create a new array containing the desired physical drives, and then on this array creating a logical drive in the required RAID scheme. For my initial tests I’m going to use a couple of HP 160GB SATA drives configured as a simple RAID 1 mirror which will hopefully give me the data resilience I need. With more drives available other options such as RAID 1+0 or RAID 5 are possible.

I want to do some testing with this configuration, including ensuring it works fine with ESXi and also by removing one of the drives to simulate a failure so I can understand how it handles an array in a degraded state and how it recovers. Assuming everything goes well and I am happy with it all I will then look at converting my current live ESXi installation over to RAID 1 scheme using the existing 250GB HP SATA drives I have. Fingers crossed it all goes OK!