Upgrade VMware ESXi ( 5.5 u1 to 5.5 u2 )
1. Move VMs using vMotion or shutdown normally
2. Insert the CD media (ESXi 5.5 Update 2)
3. Reboot ESXi host to be upgraded and boot from the DVD-ROM
4. Upgrade
5. Move or boot VMs
There is a bug in VMware ESXi 5.5 U1 for NFS APDs(All Paths Down). Because of this bug, I had a lot of trouble. If you you use the ESXi 5.5 Update 1 version, I recommend that you upgrade.