Specifications

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Make sure your system hardware complies with ESXi requirements. See Chapter 2, “System
Requirements,” on page 13 and the VMware Compatibility Guide, at
http://www.vmware.com/resources/compatibility/search.php. Check for system compatibility, I/O
compatibility (network and HBA cards), storage compatibility, and backup software compatibility.
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Make sure that sufficient disk space is available on the host for the upgrade or migration.
Migrating from ESX 4.x to ESXi 5.x requires 50MB of free space on your VMFS datastore.
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If a SAN is connected to the host, detach the fibre before continuing with the upgrade or migration.
Do not disable HBA cards in the BIOS.
NOTE This step does not apply to ESX hosts that boot from the SAN and have the Service Console
on the on the SAN LUNs. You can disconnect LUNs that contain the VMFS datastore and do not
contain the Service Console.
3 Back up your host before performing an upgrade or migration, so that, if the upgrade fails, you can
restore your host.
IMPORTANT Once you have upgraded or migrated your host to ESXi 5.x, you cannot roll back to your
version 4.x ESX or ESXi software.
4 Depending on the upgrade or migration method you choose, you might need to migrate or power off
all virtual machines on the host. See the instructions for your upgrade or migration method.
5 After the upgrade or migration, test the system to ensure that the upgrade or migration completed
successfully.
6 Reapply your host licenses. See “Reapplying Licenses After Upgrading to ESXi 5.5,” on page 214.
7 Consider setting up a syslog server for remote logging, to ensure sufficient disk storage for log files.
Setting up logging on a remote host is especially important for hosts with limited local storage.
Optionally, you can install the vSphere Syslog Collector to collect logs from all hosts. See “Providing
Sufficient Space for System Logging,” on page 23. For information about setting up and configuring
syslog and a syslog server, setting up syslog from the host profiles interface, and installing vSphere
Syslog Collector, see the vSphere Installation and Setup documentation.
8 If the upgrade or migration was unsuccessful, and you backed up your host, you can restore your host.
Files and Configuration Settings Affected by the Migration or Upgrade from
ESX 4.x or ESXi 4.x to ESXi 5.x
The migration or upgrade from ESX 4.x or ESXi 4.x to ESXi 5.x does not migrate all host configuration files
and settings.
After the upgrade, you must reconfigure some host settings.
Migrating ESX 4.x Files and Settings to ESXi 5.x
The upgrade process preserves as much of the ESX host configuration as possible. However, because of the
architectural differences between ESX 4.x and ESXi 5.x architecture, many configuration files cannot be
migrated when you select the Migrate option in the ESXi installation or upgrade wizard.
Pertinent VMware files, such as /etc/vmware/esx.conf are migrated, but many existing settings such as
third-party agents and scripts, cannot be migrated.
NOTE If a 4.x host contains customizations, such as third-party VIBS or drivers, upgrading with the
standard VMware installer ISO will result in the loss of those customizations, and possibly an unstable
system. Use ESXi Image Builder CLI to create a customized ESXi installer ISO file that includes the VIBs or
drivers. See the information on Image Builder in the vSphere Installation and Setup documentation.
vSphere Upgrade
144 VMware, Inc.