Technical Whitepaper Dell EMC PowerVault ME4 Series and Citrix XenServer Abstract This document provides best practices for deploying Citrix XenServer with Dell EMC™ PowerVault™ ME4 Series storage.
Revisions Date Description March 2020 Initial release Acknowledgements Authors: Daniel Jobke Selim Selveroglu The information in this publication is provided “as is.” Dell Inc. makes no representations or warranties of any kind with respect to the information in this publication, and specifically disclaims implied warranties of merchantability or fitness for a particular purpose. Use, copying, and distribution of any software described in this publication requires an applicable software license.
Contents Revisions................................................................................................................................................................................ 2 Acknowledgements ................................................................................................................................................................ 2 1 2 3 4 5 6 Introduction ........................................................................................................
1 Introduction This document provides examples, tips, recommended settings, and other storage guidelines a system administrator can follow while configuring a Citrix® XenServer® environment to connect to Dell EMC™ PowerVault ME4 Series storage. Frequently asked questions regarding various Dell EMC PowerVault ME4 Series storage features are also addressed.
1.4 Terminology The following terms are used throughout this document: Note: Definitions identified with an asterisk (*) are provided by the Citrix XenServer 7.6 Administrator’s Guide, which is available on the Citrix Product Documentation website. Fault domain (FD): A set of hardware components that share a single point of failure. For controller-level redundancy, fault domains are created for Dell EMC PowerVault ME4 Series storage to maintain connectivity in the event of a controller failure.
Storage Repositories (SRs)*: A Storage Repository is a particular storage target, in which virtual machine (VM) Virtual Disk Images (VDIs) are stored. Virtual Block Devices (VBDs)*: Virtual Block Devices are connector objects (similar to the PBD described previously) that allows mappings between VDIs and VMs.
2 Citrix XenServer and Dell Storage product overview This section provides an overview of Citrix XenServer and the Dell EMC PowerVault ME4 Series storage technologies presented in this paper. 2.1 Citrix XenServer Citrix XenServer is a leading server virtualization and hypervisor management platform that enables reductions in total cost of ownership for desktop, cloud, and server virtualization infrastructures.
Key features of the ME4 Series include the following: • • • • • • • • • • • • • • • • • Simple, customer-installable design Intuitive web-based GUI and CLI tools for system configuration and management All-inclusive feature-licensing model Support for all-flash, spinning, and hybrid drive configurations Linear and virtual disk group and pool configuration options Thin-provisioning with virtual disk groups for storage efficiency, along with storage tiering for intelligent rea time data placement for hot and
3 XenServer storage overview XenServer environments utilize shared storage as part of the virtualization platform. Shared storage can be connected through iSCSI, Fibre Channel (FC), SAS or NFS. The information contained in this document is focused on iSCSI block storage connectivity because the Dell EMC PowerVault ME4 Series storage platform is a block storage platform. Block storage devices in the form of iSCSI or FC LUNs are presented to the XenServer hosts, from which SRs are created.
3.2 Shared SAS/Fibre Channel storage XenServer using Dell EMC PowerVault ME4 Series storage provides support for shared SRs on FCattached/SAS LUNs using FC/SAS HBAs. Figure 3 illustrates how an environment using FC/SAS HBAs looks conceptually. Figure 3: Shared Fibre Channel storage 3.3 SR-to-VM mapping XenServer is capable of deploying a many-to-one, VM-to-SR (volume) deployment. The best number of VMs per SR largely depends on the workload and IOPS requirement of the VMs being deployed.
XenServer supports Active/Active multipathing for iSCSI and FC protocols for I/O data paths. Dynamic multipathing uses a round-robin mode load balancing algorithm resulting in active traffic on all paths during normal operation. Multipathing can be enabled using XenCenter or the command line interface. Enabling multipathing requires a restart of the XenServer host and should be enabled before storage is added to the server. Only use multipathing when there are multiple paths to the storage.
4. Check the Enable multipathing on this server box and click OK. 5. Connect to host via SSH. 6. Open /etc/multipath.conf with your favorite text editor, e.g. vi, and paste the following into the devices section. device { vendor "DellEMC" product "ME4" path_grouping_policy "group_by_prio" path_checker "tur" hardware_handler "1 alua" prio "alua" failback immediate path_selector "service-time 0" } 7. To optimize the hosts iSCSI service, edit the /etc/iscsi/iscsid.conf file and set the following values.
4 XenServer storage using Open-iSCSI initiator (software) XenServer iSCSI storage repositories are supported with Dell EMC PowerVault ME4 Series storage through the use of the Open- iSCSI initiator. Shared iSCSI SRs using the software-based host initiator are capable of supporting VM agility using XenMotion — VMs can be started on any XenServer host in a resource pool and migrated between them with no noticeable interruption.
XenCenter: Set host IQN 4.1 Open-iSCSI initiator setup with Dell EMC PowerVault ME4 Series arrays When planning an iSCSI network, isolate the iSCSI traffic from management traffic through the use of separate switches and subnets. Failure to follow this best practice may result in compromised reliability or performance.
4.2 Multipath with dual subnets Using XenServer Open-iSCSI multipathing with dual subnets to properly connect to Dell EMC PowerVault ME4 Series storage requires the following: • • • • XenServer 7.6 or later iSCSI using two unique, dedicated storage NICs and subnets.
4.2.1 XenServer Open-iSCSI initiator configuration The XenCenter management GUI can be used to configure dedicated NICs for iSCSI storage traffic use. Assigning a NIC for iSCSI use will prevent the use of the NIC for other functions such as host management. However, appropriate network configuration is also required to ensure the NIC is used for the desired traffic.
2. Select Network Settings, input the MTU of 8860 (default value is 1500), and deselect the checkbox so this network will not be added to new VMs. 3. Repeat steps 1–2 for each additional network dedicated for iSCSI storage. 4.2.2.2 Optional steps: implementing Jumbo Frames on the Dell EMC PowerVault ME4 1. In the PowerVault Manager navigate to the Home tab, click on Action and select System Settings. 2.
4.2.2.3 Required steps Note: If Jumbo Frames are to be used, the steps in section 4.2.2.1 & 4.2.2.2 must be completed prior to executing the following steps. 1. In the XenCenter management GUI, navigate to the Infrastructure view, navigate through the objects, select the desired XenServer host, select the Networking tab, and click Configure.
2. Click Add IP address, enter the desired name, select the Network from the drop-down box, and enter the IP address settings for the dedicated iSCSI storage NIC. Click OK. 3. Repeat steps 1-2 for each additional NIC dedicated for iSCSI storage.
4.3 20 Identify Dell EMC PowerVault ME4 Series storage iSCSI targets To gather Dell EMC PowerVault ME4 Series storage iSCSI target information: Within PowerVault Manager, go to the Home Tab – Action - System Settings, navigate to Ports, and click Port Settings tab. This should display the target IPv4 addresses.
4.4 Configure Host Initiators in PowerVault Manager Use the following steps to configure the host initiators for access to the Dell EMC PowerVault ME4 Series storage: 4. In XenCenter, select your host on the left-side, switch to the Storage tab and click New SR. 5. Under Virtual disk storage, select the iSCSI option, and click Next.
6. Give the new storage repository a name and click Next. 7. Depending on your license, chose between thin or thick provisioning.
8. In the Target hostname/IP address field, enter a Dell EMC PowerVault ME4 Series storage iSCSI IP addresses, and click Scan Target Host. 9. In the Target IQN drop-down list, select the option with the same *(IP Address) as you used for discovery. Leave the menu open. 10. Now switch to the PowerVault Manager Web interface and navigate to the Hosts tab. 11. On the Home tab, click Action and select Host Setup. 12. In the new window, click Next. 13.
14. Click Next 15. If desired, you can create a Host Group or join the Host to an existing Host Group. This is particularly beneficial for larger Clusters. Alternative select “Do not group this Host” and click Next. 16. Change the name, size and if desired the Pool the volume resides in. If you wish to create multiple volumes, simply click Add Row. 17. Click Next, again. 18. Confirm your host configuration by clicking Configure Host.
4.5 Creating a Storage Repository (SR) using iSCSI 1. Go back to Citrix XenCenter. 2. In the window you left open, click again on Scan Target. 3. In the Target IQN drop-down list, select the option with the same *(IP Address) as you used for discovery. 4. In the Target LUN drop-down list, select the LUN on which the new SR will reside. 5. Click Finish.
6. Confirm that you want to create a new SR: The new SR is now available to the server or pool. Repeat these steps for mapping and adding storage for any additional SRs. NOTE: For optimal performance, ensure that your VMs have the XenServer Tools installed. 5 XenServer Storage using SAS/Fibre Channel HBA XenServer Fibre Channel (FC) & SAS Storage Repositories are supported with Dell EMC PowerVault ME4 Series storage through the use of FC or SAS HBAs.
2. In the new window, click Next. 3. Enter the Host Name and select the WWPNs belonging to the host. If desired provide each Initiator ID with a NIC for easier identification. 4. Click Next 5. If desired, you can create a Host Group or join the Host to an existing Host Group. This is particularly beneficial for larger Clusters. Alternative select “Do not group this Host” and click Next. 6. Change the name, size and if desired the Pool the volume resides in.
7. Click Next, again. 8. Confirm your host configuration by clicking Configure Host. 5.2 Create SR with hardware HBA (SAS and FC) 1. In XenCenter, navigate to the XenServer pool, select the Storage tab, and click New SR. 2. Under Virtual disk storage, select the Hardware HBA option, and click Next.
3. Give the new storage repository a name and click Next. 4. Depending on your license, chose between thin or thick provisioning and click Next.
5. Select the desired LUN and click Next. 6. If this is a new SR (has not been created or used before), click Format to prepare the SR for use.
7. Click Finish to complete the SR creation process and make the SR available to the server or pool.
6 Creating & Mapping additional Volumes on Dell EMC PowerVault ME4 via PowerVault Manager 6.1 Creating a Volume: 2. On the Volumes tab, click on “Action” and select “Create virtual Volume”: 3. In the new window, give your volume a name and change the size to your needs. If you have multiple pools, you may want to change the Pool, the volume will be created on: 6.2 Mapping the Volume: 2.
3. In the new window, select your Host on the left-side and your Volume on the right-side. Note: If you want to map multiple Hosts to the same Volumes, you can either use Host-Groups or [SHIFT] / [CTRL] select multiple Hosts and or Volumes. 4. Click the blue “Map” button and proceed to click “OK” to apply the changes.
6.3 Verify multipath status To view the status of the multipath from the XenCenter GUI, select the new SR from the list of objects and expand the Multipathing dropdown section as shown in Figure 10. Display multipath status from GUI Furthermore, you can also verify that multipathing is working, using the CLI command multipath -ll: 2. Using an SSH tool, like Putty, to connect to your Host. 3.
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