Knowledge Base

Validate that each troubleshooting step below is true for your environment. Each step will provide instructions or a link to a document, in order to eliminate possible causes and take corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution.

The steps outlined below may involve terminal commands. Depending on the version of ESX used, the procedure for running terminal commands will vary:

• VMware ESXi 4.1 and later – Using Tech Support Mode in ESXi 4.1 (1017910)
• VMware ESX 4.1 and earlier – Log in to the terminal directly or by SSH as the rootuser.
• VMware ESXi 4.0 and earlier – Tech Support Mode for Emergency Support (1003677).

To troubleshoot VMware ESX to iSCSI array connectivity:

Note: A rescan is required after every storage presentation change to the environment.

1. Log into the ESX or ESXi host and verify that the host can vmkping the iSCSI targets with this command:
   
   vmkping <target ip>
   
   If you are running an ESX host, also check that the iSCSI target is pingable:
   
   ping <target ip>
   
   Note: Pinging the storage array only applies when using the Software iSCSI intitator. In ESXi, ping and ping6 both run vmkping.
   
   
2. Verify that the host Hardware Bus Adapters (HBAs) are able to access the shared storage. For more information, see Obtaining LUN pathing information for ESX hosts (1003973).
   
   
3. Confirm that no firewall is interfering with iSCSI traffic. For details on the ports and firewall requirements for iSCSI, see Port and firewall requirements for NFS and SW iSCSI traffic (1021626). For more information, see Troubleshooting network connection issues caused by firewall configuration (1007911).
   
   Note: Check SAN and switch configuration, especially if you are using Jumbo Frames (supported from ESX 4.x). To test the ping to a storage array with Jumbo Frames from ESX, run this command:
   
   vmkping -s <MTUSIZE> - <IPADDRESS OF SAN>
   
   Where MTUSIZE is 9000 - (a header of) 216, which is 8784.
   
   
   
4. Ensure that the LUNs are presented to the ESX hosts. On the array side, ensure that the LUN IQNs and access control list (ACL) allow the ESX host HBAs to access the array targets. For more information, see Troubleshooting LUN connectivity issues (1003955).
   
   
5. Verify that a rescan of the HBAs displays presented LUNs in the Storage Adapters view of a VMware ESX host. For more information, see Performing a rescan of the storage (1003988).
   
   
6. Verify your CHAP authentication. If CHAP is configured on the array, ensure that the authentication settings for the VMware ESX hosts are the same as the settings on the array. For more information, see Checking CHAP authentication on the ESX Server (1004029).
   
   
7. Consider pinging any ESX host iSCSI initiator (HBA) from the array's targets. This is done from the iSCSI host.
   
   
8. Verify that the storage array is listed on the Storage/SAN Compatibility Guide. For more information, see Verifying that ESX/ESXi host hardware (System, Storage, and I/O) devices are supported (1003916).
   
   Note: Some array vendors have a minimum-recommended microcode/firmware version to operate with VMware ESX. This information can be found from the array vendor and the VMware Hardware Compatibility Guide.
   
   
9. Verify that the physical hardware is functioning correctly, including:
   
   • The Storage Processors (sometimes known as heads) on the array
   • The storage array itself
   • Check SAN and switch configuration, especially if you are using Jumbo Frames (supported from ESX 4.x). To test the ping to a storage array with Jumbo Frames from ESX, run this command:
     
     vmkping -s <MTUSIZE> <IPADDRESS OF the storage array>

     MTUSIZE is 9000 - (a header of) 216 which is 8784
     
     
   Note: Consult your storage array vendor if you require assistance.
   
   
10. Perform some form of network packet tracing and analysis, if required. For more information, see:
    
    • Capturing virtual switch traffic with tcpdump and other utilities (1000880)
    • Troubleshooting network issues by capturing and sniffing network traffic via tcpdump(1004090)

Note: If your problem still exists after trying the steps in this article, please:

• Gather the VMware Support Script Data. For more information, see Collecting Diagnostic Information in a VMware Virtual Infrastructure Environment (1003689).
• File a support request with VMware Support and note this KB Article ID in the problem description. For more information, see How to Submit a Support Request.