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Dell EMC PowerVault ME4 Series and Citrix XenServer | H18237
3.2 Shared SAS/Fibre Channel storage
XenServer using Dell EMC PowerVault ME4 Series storage provides support for shared SRs on FC-
attached/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. When multiple
VDIs share an SR, they also share the disk queue for that SR on the host. For this reason, care should be
taken to prevent bottleneck conditions on the SR. Additionally, replication and DR become a factor when
hosting multiple VMs on an SR. This is due to replication and recovery taking place on a per-SR (volume)
basis.
3.4 Multipathing
Multipathing allows for failures in storage adapters (Open-iSCSI and HBA), switch ports, SAN switches, and
storage I/O ports. Use of multipathing is recommended to increase availability and redundancy for production
deployments of XenServer when hosting critical VM workloads.