Dynamic multipathing support is available for Fibre Channel and iSCSI storage back-ends. You can enable multipathing in XenCenter or on the xe CLI.
Before attempting to enable multipathing, verify that multiple targets are available on your storage server. For example, an iSCSI storage back-end queried for
sendtargetson a given portal returns multiple targets, as in the following example:
iscsiadm -m discovery --type sendtargets --portal 192.168.0.161 192.168.0.161:3260,1 iqn.strawberry:litchie 192.168.0.204:3260,2 iqn.strawberry:litchie
Unplug all PBDs on the host:
xe pbd-unplug uuid=pbd_uuid
Set the host’s
xe host-param-set other-config:multipathing=true uuid=host_uuid
Set the host’s
other-config:multipathhandle parameter to
xe host-param-set other-config:multipathhandle=dmp uuid=host_uuid
If there are existing SRs on the host running in single path mode but that have multiple paths:
Migrate or suspend any running guests with virtual disks in affected the SRs
Unplug and replug the PBD of any affected SRs to reconnect them using multipathing:
xe pbd-plug uuid=pbd_uuid
To disable multipathing, first unplug your VBDs, set the host
other-config:multipathing parameter to
false and then replug your PBDs as described above. Do not modify the
other-config:multipathhandle parameter as this action is done automatically.
Multipath support in XenServer is based on the device-mapper
multipathd components. The Storage Manager API handles activating and deactivating multipath nodes automatically. Unlike the standard
dm-multipath tools in Linux, device mapper nodes are not automatically created for all LUNs on the system. Device mapper nodes are only provisioned when LUNs are actively used by the storage management layer. Therefore, it is unnecessary to use any of the
dm-multipath CLI tools to query or refresh DM table nodes in XenServer. If it is necessary to query the status of device-mapper tables manually, or list active device mapper multipath nodes on the system, use the
mpathutil list mpathutil status
- Due to incompatibilities with the integrated multipath management architecture, we recommend that you do not use the standard
dm-multipathCLI utility with XenServer. Use the
mpathutilCLI tool for querying the status of nodes on the host.
- Multipath support in EqualLogic arrays does not encompass Storage I/O multipathing in the traditional sense of the term. Multipathing must be handled at the network/NIC bond level. For information about configuring network failover for EqualLogic SRs/LVMoISCSI SRs, see the EqualLogic documentation.