Here are my frustrations with vSAN. Will like feedbacks from others.
1. You cannot hot-swap or add a disk while an ESX server is up – like you can do with other storage systems. You have to shut down the server to format the disk RAID0 to be able to make it part of vSAN.
2. Often you cannot upgrade vSAN software without replacing the physical controllers on the ESXi servers. For example, I cannot go from 6.0 to 6.5 vSAN unless we replace PERC H710 controllers. (Not looking forward to it.)
3. About 20 to 25% of disk space goes to waste to make up for the fact that 1 out of 4/5 servers may go down.
4. Shutting down a ESXi server becomes much more complicated since data sitting on its disks has to be ‘evacuated’ (off-loaded) to disks of other servers, sometimes taking hours.
5. Booting up an ESXi server also takes much longer, since data on its disks has to reconciled ('initialized') with data already in production.
6. After rebooting an ESXi server, you need to wait for almost a day – while all data is resynced – before you can reboot the next ESXi server.