Best Practices for Specific Architectures

Best Practices for Specific Archite...

Exchange Server 2003

Topic Last Modified: 2005-07-26

In addition to implementing the best practices that apply to all storage architectures, you should familiarize yourself with the pros, cons, and best practices that are specific each type of storage architecture type. The following table lists these architecture types, including the pros and cons of each.

Storage architectures, including the pros and cons of each

Storage Architecture	Pros	Cons
Direct-attached storage (DAS)	Inexpensive Suitable for small to medium configurations High performance when using a RAID controller on a PCI bus or Ultra-3 SCSI	Higher management costs Not very scalable
Storage Area Network (SAN)	Can dynamically add storage Good for clusters High performance suitable for large infrastructures and data centers Supports snapshot, clones, and snapclones, which allows databases to be manageable even at very large sizes Can mirror your data to an inexpensive JBOD (just a bunch of disks) Can pool multiple vendor storage into a single unit Can pool storage on a network where it can be shared and easily provisioned Can shift resources to servers on an as-needed basis	Expensive, although this is improving Complex - requires that you have a storage expert with specific SAN knowledge Must be configured correctly or you can experience reliability problems
Network-attached storage	Inexpensive	Requires a block-mode driver for Exchange 2000, which is seldom available May not be supported on the Windows Server Catalog. You must work with your storage provider, which can cost time in a recovery scenario. Not very scalable Only allows 1,500 users per device Allows only two Exchange servers per network-attached device, limiting you to two-node cluster implementations Requires Exchange 2003 on Windows Server 2003 Does not support Volume Shadow Copy service framework for snapshots
Internet SCSI (iSCSI)	Less expensive than SANs Data can be transmitted over LANs, WANs, and over the Internet to remote storage locations iSCSI hard disks appear to be connected directly to the server	A dedicated iSCSI gigabit network separating network traffic from storage traffic is recommended.

For each storage architecture type, you must use the IOPS per mailbox value that you calculated earlier to:

Optimize for performance
Optimize for reliability

Using Storport Drivers Instead of SCSIPort Drivers

The Storport driver, a new feature in Microsoft® Windows Server™ 2003, delivers greater performance in hardware RAID and SAN environments than the preexisting SCSIport driver was capable of delivering.

In the Microsoft® Windows® operating system, the SCSIport driver, in conjunction with vendor-written adapter-specific miniport drivers, was for many years, the only driver delivering SCSI commands to the storage targets. The SCSIport driver, however, was designed to work optimally with the parallel SCSI interconnects used with direct attached storage. It was neither designed to meet the high performance standards of Fibre Channel SAN configurations, nor to work well with hardware RAID.

As a consequence, organizations running mission critical Windows applications on their servers do not realize the maximum performance benefits or manageability of their Fibre Channel SANs or hardware RAID adapters (on both the host and storage arrays) when I/O passes between the host and storage target.

These limitations have been overcome with the development of Storport, the new device driver designed to supplement SCSIport on Windows Server 2003 and beyond. Storport is a new port driver that delivers higher I/O throughput performance, enhanced manageability, and an improved miniport interface. Together, these changes help hardware vendors realize their high performance interconnect goals.

For more information about the Storport driver, see http://www.microsoft.com/WindowsServer2003/technologies/storage/storport/default.mspx.