I am currently setting up a new 3-host VSAN cluster that will be placed into production soon. (Note this is the newer "Virtual SAN" (VSAN) technology, not the older vSphere Storage Appliance (VSA) technology). This is the first time I have worked with VSAN.
Each of the three hosts in the cluster has four 1TB local HDD's and one 200GB local SSD (which VSAN needs for read/write caching) to contribute to the cluster. I have installed ESXi 5.5 directly on the first local HDD of each host.
I added the three hosts to vCenter and launched the vSphere Web Client to configure VSAN. But instead of seeing all four local HDD's on each host as being available to VSAN, only three are available.
From what I have read in the VSAN documentation, disks used by VSAN must solely be used by VSAN. That is, once VSAN "takes over" a local drive, that drive can not be used for any other purposes (such as reserving partitions for use by other OS's). However, it wasn't clear to me if that also meant not being able to store the ESXi bootable partition on one of the VSAN local drives.
I've heard a lot about installing ESXi to a bootable USB stick as an option, but have never tried it since we've always just placed the ESXi boot partition on our traditional SAN. (For background, the new VSAN cluster is going to replace our blades and traditional SAN due to downsizing and cost-cutting measures).
So to summarize, here are my questions:
- Is it possible to install ESXi to one of the local HDD's and still have the rest of the space on that HDD be available to VSAN?
- If the answer to question #1 is "no", then is the next best option to install ESXi to a bootable USB stick? (and if so, are there any notable tradeoffs to doing this that I should be aware of?)