System information

Rescan Storage Adapters
When you make changes in your ESX/ESXi host or SAN configuration, you might need to rescan your storage
adapters. You can rescan all adapters on your host. If the changes you make are isolated to a specific adapter,
rescan only this adapter.
Use this procedure if you want to limit the rescan to a particular host or an adapter on the host. If you want to
rescan adapters on all hosts managed by your vCenter Server system, you can do so by right-clicking a
datacenter, cluster, or folder that contains the hosts and selecting Rescan for Datastores.
Procedure
1 In the vSphere Client, select a host and click the Configuration tab.
2 In the Hardware panel, select Storage Adapters, and click Rescan above the Storage Adapters panel.
You can also right-click an individual adapter and click Rescan to rescan just that adapter.
IMPORTANT On ESXi, it is not possible to rescan a single storage adapter. If you rescan a single adapter,
all adapters are rescanned.
3 To discover new disks or LUNs, select Scan for New Storage Devices.
If new LUNs are discovered, they appear in the device list.
4 To discover new datastores or update a datastore after its configuration has been changed, select Scan for
New VMFS Volumes.
If new datastores or VMFS volumes are discovered, they appear in the datastore list.
Change the Number of Scanned LUNs
By default, the VMkernel scans for LUN 0 to LUN 255 for every target (a total of 256 LUNs). You can modify the
Disk.MaxLUN parameter to improve LUN discovery speed.
IMPORTANT You cannot discover LUNs with a LUN ID number that is greater than 255.
Reducing the value can shorten rescan time and boot time. However, the time to rescan LUNs might depend
on other factors, including the type of storage system and whether sparse LUN support is enabled.
Procedure
1 In the vSphere Client inventory panel, select the host, click the Configuration tab, and click Advanced
Settings.
2 Select Disk.
3 Scroll down to Disk.MaxLUN.
4 Change the existing value to the value of your choice, and click OK.
The value you enter specifies the LUN after the last one you want to discover.
For example, to discover LUNs from 0 through 31, set Disk.MaxLUN to 32.
Fibre Channel SAN Configuration Guide
56 VMware, Inc.