Installation guide

C H A P T E R 9 Storage and File Systems
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Troubleshooting SAN Issues with ESX Server
You can view LUNs through the VMware Management Interface or viewing the
output of ls /proc/vmware/scsi/<FC_SCSI_adapter>. If the output
differs from what you expect, then check the following:
• DiskMaxLUN — the maximum number of LUNs per vmhba that are scanned by
ESX Server.
You can view and set this option through the VMware Management Interface
(Advanced Settings in the Options page) or by viewing this setting through
/proc/vmware/config.
• DiskSupportSparseLUN — if this option is on, then ESX Server scans past any
missing LUNs. If this option is off, ESX Server stops scanning for LUNs if any LUN
is missing.
You can view and set this option through the VMware Management Interface
(Advanced Settings in the Options page) or by viewing this setting through
/proc/vmware/config.
• LUN masking — With LUN masking, each LUN is exclusively assigned and
accessed by a specific list of connections. Be sure that LUN masking is
implemented properly and that the LUNs are visible to the HBAs on ESX Server.
• Zoning — Zoning limits access to specific storage devices and increases security
and decreases traffic over the network. If you use zoning, be sure that zoning on
the SAN switch is set up properly and that all vmhba and the controllers of the
disk array are in the same zone.
• Storage controller — If a disk array has more than one storage controller, then
make sure that the SAN switch has a connection to the controller that owns the
LUNs you wish to access. On some disk arrays, only one controller is “active” and
the other controller is “passive” until there is a failure. If you are connected to the
wrong controller, then you may not see the expected LUNs, or you may see the
LUNs, but may get errors when trying to access them.
For more information on using SANs with ESX Server, be sure to check the Knowledge
Base on the VMware Web site at www.vmware.com/support/.