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BP1013 Best Practices for Enhancing Microsoft Exchange Server 2010 Data Protection and Availability 46
VSS timeout
Under rare circumstances of extreme load, the VSS service can time out when a requester
makes an inquiry to create a shadow copy. Follow Microsoft resolution advice to correct this
problem. Evaluate an increase of the VSS timeout value in the registry configuration editor if
required.
General network best practices
• Use separate network infrastructures for the isolation of the LAN traffic from the SAN traffic
(iSCSI).
• Use redundant elements (switches, ISLs) to provide a reliable network infrastructure
• Enable flow control for the switch ports where the PS Series arrays are connected
• Enable jumbo frames (large MTU) for the switch ports where the PS Series arrays are
connected
• Disable spanning tree for the switch ports where the PS Series arrays are connected, and
enable Portfast instead
• Evaluate jumbo frames (large MTU) for the LAN network when appropriate (limited by type of
devices the traffic traverses)
General storage best practices
• Dedicate separate pools for databases connected to nodes in a DAG. Do not share the same
disks for active and passive copies of an Exchange mailbox database.
• Choose the appropriate RAID level.
o RAID-50 offers a good combination of performances and capacity requirements for
Exchange mailbox database deployments
o RAID-10 offers greater write data operations at a lower capacity levels
o RAID-5/6 offer good performances and greater capacity. Supported by Microsoft, and
requires careful validation if considered for deployment.
• Distribute the controllers network port connections appropriately to each network switch
• Use MPIO DSM provided by EqualLogic HIT Kit
General ESX and Virtual Machines best practices
• Use separate virtual switches for Virtual Machines with network traffic and iSCSI storage traffic
• Use Port Group and VLAN tagging to logically segregate different kinds of LAN traffic
• Enable jumbo frames (large MTU) for the iSCSI virtual switch
• Evaluate jumbo frames (large MTU) for the Virtual Machines virtual switch as well
• Use at least two physical network adapters for each virtual switch to achieve redundancy
• Use a guest OS iSCSI initiator when using ASM/ME to allow client integration with the SAN
• Use performance optimized network adapters of the type VMXNET3 for guest iSCSI
connections (VMware tools required)
• Enable TSO and LRO on the guest network adapters for iSCSI storage traffic
• Do not allocate more virtual CPU than is really required in the virtual machines
• Do not overcommit memory on ESX hosts. Exchange virtual machines have a memory
intensive workload.