Some vSphere5 and vCenter5 upgrade considerations

While preparing for my VCP5 exam I was reading a lot of material including the upgrade guide.

As with all upgrade, not all upgrade paths are supported. That’s why I thought to make a list with some upgrade considerations.

1. vSphere5 only comes with the ESXi hypervisor architecture. The main distinction is that ESX comes with a Service Console (also called SC or COS from Console Operating System) and ESXi only has a tech support mode (busybox implementation). If you want to perform command-line administration, you can use vCLI or PowerCLI.
2. You can upgrade from ESX 3.5/4.x and ESXi 4.x installations to ESXi 5.0 preserving your VMFS partitions.
3. New installation and boot devices options are:
   • Unified Extensible Firmware Interface (UEFI) like USB
   • Disk larger than 2TB if the system firmware supports it.
4. A minimum of 2098MB or RAM is required.
5. No graphical installer is available because this requires a Service Console.
6. The (text-base) installer can be used for new installations or upgrades
7. New partitions use the GUID partition table (GPT) instead of the MBR. GUID supports partitions size larger than 2TB.
8. New installations create a 4GB scratch partition. Any remaining disk space is formatted as VMFS datastore.
9. Rolling back to a previous version of ESX/ESXi is not supported.
10. When using a kick-start script (ks.cfg) you can press Shift-O when the ESXi installer screen appears to edit the boot options and provide the kick-start script (Example: ks=nfs//192.168.1.10/vSphere-install/esxi5.cfg nameserver=192.168.1.10 ip=192.168.1.1 netmask=255.255.255.0 gateway=192.168.1.254)
11. The default database for vCenter 5 is Microsoft SQL Server 2008 R2 express. This is bundled with the vCenter DVD. Requirements are:
    • Microsoft Windows Installer version 4.5 (MSI 4.5)
    • 4GB RAM
    • 4GB Disk Storage
    • 64 Bits Operating System
12. A in-place upgrade on Windows XP is not supported
13. When doing a in-place upgrade of your vCenter server, your vCenter server can be down for 40 till 50 minutes. During this downtime, DRS will not function. HA will.
14. A in-place upgrade on a 32Bits Operating System is not supported. You have to perform a migration to a 64Bits Operating System.
15. There is also a vCenter appliance available. This appliance is based on SUSE Linux Enterprise Server 11 (SLES11).
16. Some configuration files are not migrated when performing a upgrade:
    • /etc/sysconfig/mouse
    • /etc/sudoers
    • /etc/yp.conf
    • Custom scripts that are added to /etc/rc.d
17. Configuration files that are migrated are:
    • /etc/vmware/esx.conf
    • /etc/ntp.conf, ntp.drift, ntp.keys
    • /etc/krb.*, /etc/krb5.*
    • /etc/hosts, /etc/resolv.conf
    • /etc/pam.d/*
    • /etc/vmware/vmkiscsid/*
18. Configuration files that are partially migrated are:
    • /etc/passwd, /etc/shadow (only root and vpxusers accounts)
19. When performing a new vSphere5 installation the default partition table that is used will be GPT. When performing a in-place upgrade the MBR partition format will be kept.
20. When migration from ESX the Service Console network interface cards (NICs) are converted to VMkernel NICs and the Service Console port group is removed.
21. Rule set files and customized firewall rules are not preserved.
22. You cannot perform a in-place upgrade from ESX4.x to ESXi 5.0 when the ESX4.x was upgraded from ESX3.x.
23. When performing a in-place upgrade from ESX 4.x the /boot partition has to have more than 350Mb of free space. If the hosts that you are upgrading does not have more than 250MB of free space in the /boot partition, use a scripted or interactive upgrade instead.
24. You can preserve your (local) VMFS datastores when upgrading. Afterward you can upgrade your VMFS3 datastore to VMFS5.