Fault symptom:
Citrix XenServer is a complete server virtualization platform built on the open-source Xen system Hypervisor. XenServer is another server virtualization platform except VMware vSphere. Server virtualization is a proven technology that allows multiple virtual machines to run on a single physical server. Each virtual machine is completely isolated from other virtual machines and is separated from the basic host through the software layer of the hypervisor. In this way, each virtual machine can run different operating systems and applications. Because these virtual machines are separated from the basic host, they can also be moved from one physical server to another without interrupting the operation, that is, real-time migration. These attributes are changing the way enterprises implement virtual computing.
This article describes the main configuration steps and precautions for XenServer when using emc vnx or CLARiiON series storage.
Solution:
Deployment Type:
When emc vnx or CLARiiON arrays are selected as backend storage, XenServer provides available shared storage deployment solutions, including iSCSI, fiber Channel (hardware HBA), and StorageLink Gateway. These three deployment types support XenMotion (similar to VMware vMotion)-virtual machines can be started on any host in the resource pool and can be freely migrated between them.
ISCSI:
Fiber Channel:
StorageLink Gateway:
Configuration steps:
Enable Multipath support for XenServer:
Open XenCenter and connect to the Resource Pool ). To enable multi-path support, XenServer must enter the Maintenance Mode ). Multi-path support must be enabled for each host in the resource pool:
1. Right-click XenServer and click Enter Maintenance Mode
2. If this XenServer is a Pool Master host, you need to specify a new Master. XenMotion migrates the VM running above to another host in the pool.
3. After entering the Maintenance Mode, right-click XenServer and select Properties
4. Select the Multipathing option and check Enable multipathing on this server.
5. If you set the Pool Master to Maintenance Mode, it takes some time for XenCenter to reconnect to the new Master. The operation can continue only after the XenCenter is connected back to the new Pool.
6. Right-click XenServer and choose Exit Maintenance Mode to Exit the Maintenance Mode.
7. Repeat the preceding operations on all hosts in the storage pool.
Configure VNX or CLARiiON:
Operations required in advance on VNX or CLARiiON include network settings, product registration, port configuration, security settings, cache settings, creation of Storage Group, RAID Group, and LUN. Next, register the XenServer host to VNX or CLARiiON based on different connection types and add it to the corresponding Storage Group. Note that the VNX/CLARiiON Failover Mode value for XenServer is as follows:
Initoator Type: CLARiiON Open
Failover Mode: 4 *
* Note: Failover Mode 4 is the asynchronous Active/Active Mode. It is based on EMC's ALUA (asypolicric Logical Unit Access, asynchronous Logical Unit Access) technology. For detailed technical details about emc alua, refer to the white paper EMC CLARiiON asypolicric Active/Active Feature. In addition, we also noticed that a few users experienced performance degradation when setting the Failver Mode to 4, or the users used the series earlier than CLARiiON CX3 and did not support the ALUA Mode. Because XenServer can be considered as a Linux instance at the same time, you can set the Failover Mode to 1 by referring to the instructions in the detailed configuration of the Failover for various hosts in the document. Note that changing the Failover Mode requires that the host be offline ).
