Oracle Solaris iSCSI Technology (Overview)

iSCSI is an acronym for Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage subsystems.

By carrying SCSI commands over IP networks, the iSCSI protocol enables you to access block devices from across the network as if they were connected to the local system.

If you want to use storage devices in your existing TCP/IP network, the following solutions are available:

• iSCSI block devices or tape – Translates SCSI commands and data from the block level into IP packets. Using iSCSI in your network is advantageous when you need to have block-level access between one system and the target device, such as a tape device or a database. Access to a block-level device is not locked so that you could have multiple users or systems accessing a block-level device such as an iSCSI target device.

• NFS – Transfers file data over IP. The advantage of using NFS in your network is that you can share file data across many systems. Access to file data is locked appropriately when many users are accessing data that is available in an NFS environment.

Here are the benefits of using iSCSI targets and initiators in Oracle Solaris:

• The iSCSI protocol runs across existing Ethernet networks.

  • You can use any supported network interface card (NIC), Ethernet hub, or Ethernet switch.

  • One IP port can handle multiple iSCSI target devices.

  • You can use existing infrastructure and management tools for IP networks.

• You might have existing Fibre-Channel devices that can be connected to clients without the cost of Fibre-Channel HBAs. In addition, systems with dedicated arrays can now export replicated storage with ZFS or UFS file systems.

• There is no upper limit on the maximum number of configured iSCSI target devices.

• The protocol can be used to connect to Fibre Channel or iSCSI Storage Area Network (SAN) environments with the appropriate hardware.

Here are the current limitations or restrictions of using the Solaris iSCSI initiator software:

• Support for iSCSI devices that use SLP is not currently available.

• Boot support for iSCSI devices is not currently available.

• iSCSI targets cannot be configured as dump devices.

• iSCSI supports multiple connections per session, but the current Solaris implementation only supports a single connection per session.

• Transferring large amounts of data over your existing network can have an impact on performance.

Identifying Solaris iSCSI Software and Hardware Requirements

• Solaris iSCSI software and devices

• Solaris 10 release (at least the 1/06 release) for Solaris iSCSI initiator software

• Solaris 10 release (at least the 8/07 release) for Solaris iSCSI target software

• The following Solaris 10 software packages:

  • SUNWiscsir – Sun iSCSI Device Driver (root)

  • SUNWiscsiu – Sun iSCSI (usr)

  • SUNWiscsitgtr – Sun iSCSI Target (root)

  • SUNWiscsitgtu – Sun iSCSI Target Management Utilities (usr)

• Any supported NIC

Oracle Solaris iSCSI Terminology

Review the following terminology before configuring Oracle Solaris iSCSI initiators.

Recommended iSCSI Configuration Practices

Review the following iSCSI recommendations before configuring iSCSI devices in your network.

• Devices

  • Consider using multipathed device paths for increased availability.

  • Multiple connections per session (MCS) support allow multiple TCP/IP connections from the initiator to the target for the same iSCSI session.

• Network

  • Deploy iSCSI devices in a fast (gigE or better), dedicated network.

  • Use jumbo frames, if possible to allow more data to be transferred in each Ethernet transaction to reduce the number of frames.

  • Use CAT6 rated cables for Gigabit network infrastructures.

  • Segregate iSCSI storage networks from your local area network traffic

  • Configure multiple sessions or connections to utilize multiple threads in TCP/IP stack

  • Consider TCP tuning, such as disabling Nagle algorithm

• Security

  • In addition to physical security, use CHAP authentication, which ensures that each host has its own password.

  • Consider using iSNS target discovery domains, which enhance security by providing access control to targets that are not enabled with their own access controls, while limiting the login process of each initiator to a relevant subset of the available targets in the network.