iSCSI overview
iSCSI is an Internet Protocol-based (IP-based) method that is
designed to send small computer systems interface (SCSI) commands that are
encapsulated in IP packets over TCP/IP networks. Users and applications request
and receive data from high-performance data storage devices over standard
network switches and over IP routers. Because iSCSI is IP-based, data can be
transmitted over local area networks (LANs), over wide area networks (WANs),
and over the Internet to remote storage locations. Microsoft operating systems
display iSCSI hard disks to users and to programs such as Exchange Server 2003
or Exchange 2000 Server as hard disks that are connected directly to the user's
computer.
iSCSI deployment
Microsoft encourages you to use caution when you deploy Exchange
Server 2003 with iSCSI or Exchange 2000 Server with iSCSI. Because iSCSI uses
the SCSI transport protocol to transmit block data over TCP/IP networks, the
involvement of a network can introduce components that are not traditionally
thought of as high-speed input/output paths. To maximize , make sure that the
networking components that are involved in the data path are suited for high
bandwidth iSCSI disk transfers. To make sure that bandwidth is reliably
available for disk transfers, we also recommend that you do not share the disk
I/O path with other network traffic.
Hardware selection
If the fibre channel storage area network (SAN) hardware or the
iSCSI SAN hardware has passed the Designed for Windows Logo Program for iSCSI
hardware devices, the hardware is also supported by Exchange Server 2003 and by
Exchange 2000 Server. In other words, no additional qualification for Exchange
Server 2003 or for Exchange 2000 Server is provided under the Designed for
Windows Logo Program. You can view hardware components that are qualified under
the Designed for Windows Logo program for Microsoft Windows 2000 and for
Microsoft Windows Server 2003 in the Windows Server Catalog. For more
information about the Windows Server Catalog, visit the following Microsoft Web
site:
For more information about support for direct attached storage
(DAS), network attached storage (NAS), or storage area networks (SANs) in Exchange Server, click the following article number to view the article in the Microsoft Knowledge Base:
317173
Exchange Server and
network-attached storage
Microsoft requires that storage systems
for Exchange Server data on clustered servers be qualified for cluster
implementations and designed to support Exchange Server data. A storage system
that performs well in a non-clustered environments may not be suitable for use
in a cluster. If you plan to use SAN or iSCSI solutions in clustered Exchange
environments, Microsoft strongly recommends that you verify that the complete
clustering solution has passed the Microsoft Cluster Hardware Compatibility
Test (HCT) testing and received the �cluster qualified� solution logo. If you
combine individual components and devices, Microsoft does not guarantee that
the specific arrangement is supported in a clustered configuration. This is
true even if all individual components are listed in the Windows Server
Catalog.
Microsoft also recommends that you consider specific
functionality requirements when you select your hardware. For example, online
snapshot backup is supported when you use the Volume Shadow Copy service on
iSCSI hardware that has an appropriate Volume Shadow Copy service hardware
provider.
For more information about the Volume Shadow Copy service, click the following article number to view the article in the Microsoft Knowledge Base:
822896
Exchange Server 2003 data backup
and Volume Shadow Copy services
For more information about how to configure clustered Exchange servers, click the following article number to view the article in the Microsoft Knowledge Base:
317173
Exchange Server and
network-attached storage
For more information about iSCSI hardware
that has passed the Designed for Windows Logo Program, visit the following
Microsoft Web site:
Microsoft recommends that you use Gigabit Ethernet. Gigabit
Ethernet has error rates that are similar to fibre channel. If your storage
area network (SAN) that supports your Exchange environment uses fibre channel
or iSCSI, Microsoft recommends that you contact your SAN storage vendor for
performance and configuration recommendations.
Hardware performance evaluation
Microsoft recommends that you use Microsoft-provided performance
evaluation tools such as Jetstress to test your DAS configuration, SAN
configuration, or NAS configuration to verify that the configuration meets
performance requirements.
For more information about Jetstress, visit
the following Microsoft Web site:
Microsoft iSCSI Initiator service
Persistent targets are devices that are identified by the
same IP or by media access control (MAC) address in each session. The use of
persistent targets requires that Exchange services are dependant on the
Microsoft iSCSI Initiator service (msiscsi). The Initiator service is a service
that manages all iSCSI initiators, including network adapters and host bus
adapters (HBAs) on behalf of the operating system. The iSCSI Initiator service
aggregates discovery information and manages security.
To make the
volumes persistent, Microsoft recommends that you use the iSCSI command line
interface (ISCSICLI) command
persistentlogintarget or
the iSCSI Initiator Control Panel tool. To permit the iSCSI service to
configure the list of persistent volumes, you can use the ISCSICLI command
bindpersistentvolumes or the iSCSI Initiator Control
Panel tool.
Note If you make any services dependent upon the Microsoft iSCSI
initiator service, you must manually stop the service before you upgrade or
remove the Microsoft iSCSI initiator package.
Additional information
Exchange 2007: Storage Technology
http://technet.microsoft.com/en-us/library/bb738146(EXCHG.80).aspxExchange 2010: Understanding Storage Configuration
http://technet.microsoft.com/en-us/library/ee832792.aspxFor more information about iSCSI technology and Microsoft support
of iSCSI, visit the following Microsoft Web site: