vSphere 5.1 - Issues and Limitations you need to know

[Last Update: 8. Jan 2013]

VMware vSphere 5.1 is now global available since about one week. It's time to wrap up the issues and limitations you should know if you are planning to upgrade your environment. I am tracking all of this issues and will report if there are any changes. Please subscribe if you want to get notified.

PowerPath/VE 5.7 does not load on ESXi 5.1
For me, this is the worst issue in 5.1. If have an EMC storage and using the PowerPath multipathing policy your ESXi may fail with a purple screen of death (PSOD) #PF exception 14 in world 75363:sfcb-CIMXML.
There is no fix or workaround for this issue: Do not Upgrade!
This issue has been fixed in patch ESXi510-201210001
VMware KB2034796: PowerPath/VE 5.7 does not load on VMware vSphere version 5.1
EMC KB302625: PowerPath/VE will not load with VMware vSphere 5.1 

EMC Symmetrix VMAX/VMAXe datastore creation fails
When your ESXi host is connected to a VMAX/VMAXe array any try to create a VMFS5 datastore, the following error message appears: An error occurred during host configuration. The error is a result of the ATS (VAAI) portion of the Symmetrix Enginuity Microcode (VMAX 5875.x) preventing a new datastore on a previously unwritten LUN.
VMware has provided a solution for this issue:
VMware KB2032691

Missing Performance history in vCenter Server 5.1
You see only the last 30 days of performance history in the Past Year view
There is no fix or workaround for this issue
VMware KB2042164

The vShield Data Security vApp is broken after an upgrade to vSphere 5.1
If you have vShield Endpoint in your environment you have to consider a possible downtime during the upgrade. The vShield vApp appears as orphaned and the User Interface shows vShield Endpoint as uninstalled.
There is a workaround for this issue: Reinstall vShield Endpoint.
VMware KB2031655: After upgrading to vSphere 5.1, vShield Endpoint stops functioning

vCenter Services hang on startup after upgrade from vSphere 4.0 to vSphere 5.1
If you have a self-signed certificate created with vSphere 4.0 you might run into this issue. This is caused by certificated created with a less than 2048-bit key.
VMware has provided a solution for this issue:
VMware KB2035623: vCenter Server Services hang on startup after upgrading to vCenter Server 5.1
1. Identify that the length of the encrypted password for any host does not meet the 2048-bit key length:
SQL query: SELECT ID, LEN(PASSWORD), PASSWORD FROM VPX_HOST;
2. If any lengths are found to be less than 345, clear out the stored encrypted passwords
SQL query: UPDATE VPX_HOST SET PASSWORD='';
3. Restart vCenter Server Service.

vCenter Server Appliance is broken after upgrade to vSphere 5.1
The following error message might appear in the vpxd.log file: [RefreshSsoToken] AcquireToken exception: Unexpected SOAP fault: ns0:FailedCheck; request failed. This issue is caused by an invalid certificate.
Doublecheck your certificate prior to upgrade.
VMware KB2030695: vpxd service fails to start after you upgrade from vCenter Server Appliance 5.0.x to 5.x

A wrong vCenter DNS Name might cause several Problems with the vSphere Web Client
I encountered several issues with the new vSphere Web Client caused by incorrect vCenter Hostname settings. This was also an issue with 4.x and 5.0 but it usually remains undetected. Please check the following vCenter Server Advanced Settings (Administration > vCenter Server Settings... > Advanced Settings) prior to update:
- VirtualCenter.FQDN
- VirtualCenter.VimApiUrl
- VirtualCenter.VimWebServicesUrl

Missing support for vCloud Connector 1.5 and VMware View
If you are using VMware View or vCloud Connector 1.5: Do not Upgrade!
VMware View is supported with patch ESXi510-201210001
VMware KB2035504: VMware vCloud Connector 1.5 does not support VMware vSphere 5.1
VMware KB2035268: vSphere 5.1 is not supported with any versions of VMware View

NFS and iSCSI performance problems with Synology Storage
Synology Users have reported massive issues with vSpehre 5.1. Access to iSCSI and NFS Datastores is faulty. Kendrick Coleman has a lot of information and some news about this problem: Synology Users DO NOT Upgrade To vSphere 5.1. Synology is working on this issue.

Additional non-critical issues addressed by VMware
VMware KB2035413: Upgrading vCenter Server 5.1 fails with the error: Certificate already expired
VMware KB2034975: vCenter Server 5.1 start up may take longer than previous versions
VMware KB2033232: InvalidLogin exceptions are logged after you install vCenter Server 5.x
VMware KB2031263: Error 29453 during upgrade of vSphere Authentication Proxy version 5.1
VMware KB2034844: vSphere Web Client 5.1 interface does not reflect most recent state changes