Module 07 Multi Vendor iSCSI Initiators 14pages

7/28/2019 Module 07 Multi Vendor iSCSI Initiators 14pages

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dule 7 Multi-Vendor iSCSI Initiators


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iSCSI offers a choice of initiators from software (standard NIC or TOES) to hardware

(HBAs).

NIC- Gigabit Ethernet is processed in hardware while the rest of the protocol

stack is processed in software.

HBA Gigabit Ethernet, TCP/IP, and iSCSI are all processed in hardwarewhile the rest of the protocol stack is processed in software.

TOE TCP/IP offload engine - Gigabit Ethernet, TCP/IP, are processed in

hardware while the rest of the protocol stack is processed in software.

Pros and cons of hardware vs. software initiators

A NIC is cheaper than an HBA

Where processing is handled:

NIC only process: The Gigabit Ethernet frame information is on the

card.

TCP/IP, iSCSI and SCSI and application/ file system processes are

done in software.

HBA process: The Gigabit Ethernet, TCP/IP, and iSCSI tasks are on the

card while the SCSI and application/file system processes are done in

software, typically resulting in higher performance than a NIC.

iSCSI HBAs are much less expensive per port than the FC HBAs. Based on Gartner

estimates, these differences will expand in iSCSIs favor due to commoditization and

volumes of Ethernet networks.



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Allows boot from SAN, isolation of iSCSI traffic from other TCP/IP traffic. May

increase performance due to offloading of iSCSI, Network and Hardware.

HBA should also be considered for boot from SAN applications. Boot from SAN is

possible using software initiator/NIC, but may be harder to set up and manage thanan HBA.

HBAs are useful in non-Windows environments to ensure egress port binding

Most non-Windows software initiators dont provide a way to bind iSCSI

traffic to a particular NIC



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The Software iSCSI Initiator enables connection of a host to an external iSCSI storage

array using Ethernet NICs, TCP offloads or even some iSCSI HBAs.

Not shown above but worth mentioning is the 10GB Converged Network Adapter

(CNA). CNAs offer server administrators the opportunity to consolidate LAN, NAS,iSCSI SAN and Fibre Channel SAN connectivity onto a single adapter.



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To verify whether sector alignment has been performed run the DiskPart (DiskPar if

on Windows 2000) utility.

Example:

DISKPART> select disk 0

Disk 0 is now the selected disk.

DISKPART> list partition

Partition ### Type Size Offset

------------- ---------------- ------- -------

Partition 1 Primary 119 GB 64 KB



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Whether it is a software or hardware initiator, the basic requirements for connectingto a target are the same.

The following are required:

Target information (normally the targets IP address)

Discovery of volumesLogin to the desired volumes

Bind the volume

Done in the iSCSI initiator control panel

Persistent target means that the initiator will login to that volume the nexttime it reboots

The customer must then assign a drive letter to the file system, i.e. NTFS

Assigning a drive letter to the file system happens in Disk Management.

Binding (a.k.a Bound Volumes) is the process whereby the iSCSI initiatorensures that a volume has been logged in and that the drive letter assigned toit is visible before returning control to the boot process. This ensures thatany subsequent applications will always have their data drives available. Thisis strictly a function of the initiator.



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Avoid common problems relating to both hardware and software initiators:

Make sure the latest BIOS is installed on the server motherboard

Confirm that the latest BIOS is installed on the HBA

Confirm that the latest drivers are installed



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Storport is the new Microsoft port driver recommended for use with hardware RAID

storage arrays and high performance Fibre Channel interconnects. Storport

overcomes the limitations of the legacy SCSIport design while preserving enough of

the SCSIport framework that porting to the Storport device is straightforward for

most developers. Storport enables bidirectional (full duplex) transport of I/O requests,

more effective interactions with vendor miniport drivers, and improved management

capabilities. Storport should be the port driver of choice when deploying SAN or

hardware RAID storage arrays in a Windows Server 2003 environment.

Storport is about 30-50% more efficient than SCSIport, passing through more I/O per

second than SCSIport and using less CPU to do so.



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Module 07 Multi Vendor iSCSI Initiators 14pages

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