Linux on System z: iSCSI Initiator Configuration Linux on System z: iSCSI Initiator Configuration Note Before using this information and the product it supports, read the information in “Notices” on page 27. Contents Figures ...............v Discovering iSCSI targets using Send Targets . 12 Logging in to discovered targets .......13 About this publication ........vii Logging out from targets ..........13 Discovering and logging in to targets using YaST (SUSE-specific) .............13 Chapter 1. Introduction ........1 Logging out from iSCSI targets using YaST iSCSI initiators and targets..........1 (SUSE-specific) .............19 Generating an iSCSI qualified name ......2 Automatic iSCSI target discovery and login (persistent across subsequent reboots) .....22 Chapter 2. Setting up iSCSI at the Avoiding data corruption or loss .......23 Storwize V7000 clustered system ....3 Creating an iSCSI host on Storwize V7000 ....3 References .............25 Mapping iSCSI volumes to the iSCSI host on the Storwize V7000 system ...........8 Notices ..............27 Trademarks ..............29 Chapter 3. Setting up iSCSI initiator Terms and conditions ...........29 software on Linux on System z ....11 Installing iSCSI initiator software on Linux on Index ...............31 System z ...............11 Setting the iSCSI qualified name for the Linux host 12 © Copyright IBM Corp. 2013 iii iv Linux on System z: iSCSI Initiator Configuration Figures 1. iSCSI architecture ...........1 12. Volume mapped successfully.......10 2. iSCSI host connection to Storwize V7000 over 13. List of iSCSI volumes with updated Host Ethernet network ...........2 Mappings information .........10 3. No iSCSI host on Storwize V7000 .....4 14. iSCSI Initiator Overview window .....14 4. Create Host window ..........4 15. iSCSI Initiator Discovery window .....15 5. Entering host name details ........5 16. iSCSI Initiator Discovery ........16 6. Adding iSCSI ports ..........6 17. Select No Authentication ........17 7. Port definitions............7 18. Target is connected ..........18 8. Create Host window - host is successfully 19. Connected targets ..........19 completed .............8 20. Connected Targets ..........20 9. Overview .............8 21. Click Continue to confirm log out. .....21 10. Listed iSCSI volumes..........9 22. Successful logout...........22 11. Mapped volumes ...........9 © Copyright IBM Corp. 2013 v vi Linux on System z: iSCSI Initiator Configuration About this publication This white paper describes the basic configuration of Internet Small Computer Systems interface (iSCSI) initiator when Storwize® V7000 used as a iSCSI target. This white paper is written on the basis of SUSE Linux Enterprise 11 SP2 and Red Hat Enterprise Linux 6.4 results. To provide a more complete picture of the configuration used in this white paper the iSCSI setup at Storwize V7000 is also briefly described. The following IBM® storage products support iSCSI: v IBM Storwize V7000 v IBM XIV® Storage System v IBM System Storage® DS5000 Series v IBM System Storage DS5020 Express® v IBM System Storage DCS3700 v IBM Storwize V3700 v IBM System Storage v DS3500 Express Linux on System z® supports the following SCSI transports: v Fibre Channel Protocol (FCP), mapping of SCSI over Fibre Channel v iSCSI, mapping of SCSI over TCP/IP FCP provides faster and more reliable access as compared to the iSCSI transport. But iSCSI is more cost effective than FCP. Scope of this document Advanced topics such as iSCSI multipath and iSCSI security are out of the scope of this document Note: Although multipathing is not described in this document, it is strongly recommended for production environments. Author Deepak P Joshi Linux on System z Prerequisites v Red Hat Enterprise Linux 6 or SUSE Linux Enterprise Server 11 distribution installed on System z with the network configured. There must be connectivity between the Linux system and Storwize V7000. Linux on System z supports the following types of network connection: – Network connections through Open Systems Adapter (OSA) - works in Layer-2 or Layer-3 mode – HiperSockets © Copyright IBM Corp. 2013 vii – GuestLAN – Virtual Switch Even though the above network connections are supported, the network connection must be configured through OSA either in Layer-2 or Layer-3 mode for the iSCSI configuration. In the z/VM® environment the Virtual Switch network connection with rdev option enabled can also be used for the iSCSI configuration. HiperSockets™ and GuestLAN network connections cannot be used for the iSCSI configuration. For more information about network connections with Linux on System z, see Device Drivers, Features and Commands: – Reference for SUSE Linux Enterprise Server 11 SP2: http://www.ibm.com/developerworks/linux/linux390/documentation_suse.html#sles11sp2 – Reference for Red Hat Enterprise Linux 6.4: http://www.ibm.com/developerworks/linux/linux390/documentation_red_hat.html#rhel64 v Storwize V7000 already configured with iSCSI LUNs and iSCSI target (iSCSI host object) created and mapped with iSCSI LUNs. v The IP address of the iSCSI portal and IQN of iSCSI target (iSCSI host object) at Storwize V7000 Restrictions v Storwize V7000 supports only one iSCSI session between an initiator and target at a time v There is no support for ipl'ng from Linux on system z viii Linux on System z: iSCSI Initiator Configuration Chapter 1. Introduction A brief introduction to the architecture of the Internet Small Computer System Interface (iSCSI) standard. iSCSI is a standard for IP-based (TCP/IP) storage networking, which allows SCSI commands to be transferred over an IP-based network. It also facilitates the block-level transfer of SCSI commands over IP (TCP/IP) network. The architecture of iSCSI is similar to that of a client/server architecture, where an initiator acts as the client that issues an I/O request and the target (a device in the storage system) acts as a server. Distance extension can be achieved by this architecture when used over IP networks. There are two kinds of iSCSI initiators: v Software-based initiator v Hardware-based initiator The software-based initiator is a driver that pairs the network interface driver and the SCSI block-level driver together to handle the iSCSI requests. A hardware-based initiator is an iSCSI Host Bus Adapter (HBA), which is similar to Network Interface Controller (NIC) with an on-board Application-Specific Integrated Circuit (ASIC) to offload iSCSI work from the system CPU. System z uses the software-based iSCSI initiator which in turn means it does not support the offloading of iSCSI work. TCP/IP network iSCSI initiator iSCSI target Figure 1. iSCSI architecture iSCSI initiators and targets A Network Interface Controller (NIC) on System z attached to an IP (TCP/IP) network acts as an iSCSI initiator which initiates I/O requests to and receives responses from iSCSI target. In this case the target is Storwize V7000. iSCSI targets are the devices, which provide the response to iSCSI commands received from the iSCSI initiators over the IP (TCP/IP) Network. On Storwize V7000, one or both of its node Ethernet ports are configured to become iSCSI target. Initiators and targets are given a unique ASCII name with a size of 233 bytes known as iSCSI Qualified Name (IQN). IQN is worldwide unique name which is used to identify each initiator and target. © Copyright IBM Corp. 2013 1 Figure 2. iSCSI host connection to Storwize V7000 over Ethernet network Figure 2 courtesy of Storwize V7000 Information Development. For more information about Storwize V7000, see: http://pic.dhe.ibm.com/infocenter/storwize/ic/index.jsp Generating an iSCSI qualified name A unique iSCSI qualified name (IQN) can be generated by the utility iscsi-iname and it is generated every time you invoke iscsi-iname. This IQN can be used to configure iSCSI initiator and the iSCSI target. Note: The IQN should be the same at both the iSCSI initiator and iSCSI target. Example: # iscsi-iname iqn.2012-02.com.ibm.de.boeblingen:01:c5f446d488f4 2 Linux on System z: iSCSI Initiator Configuration Chapter 2. Setting up iSCSI at the Storwize V7000 clustered system The iSCSI setup at Storwize V7000 is briefly described for the completeness of this document. It is assumed that the storage administrator has already set up the Storwize V7000 clustered system. 1. Get the iSCSI Qualified Name (IQN) for the Linux host system and iSCSI portal IP address from the Storwize V7000 storage administrator. 2. Configure IPv4 or IPv6 addresses for the system Ethernet ports on the nodes that are in the I/O groups that use the iSCSI volumes. 3. Create iSCSI volumes on the Storwize V7000 system. 4. Create a host object on the Storwize V7000 system server that describes the iSCSI server initiator to which the volumes are to be mapped, see “Creating an iSCSI host on Storwize V7000.” 5. Map the volume to the host object in the Storwize V7000 system, see “Mapping iSCSI volumes to the iSCSI host on the Storwize V7000 system” on page 8. Considerations v Each connection between a host initiator and a Storwize V7000 system Ethernet port can use either IPv4 or Ipv6. Concurrent use of both IPv4 and Ipv6 is not supported. v Storwize V7000 Ethernet ports 1 and 2 can each be configured for both a cluster IP address and an iSCSI target IP address. v A different cluster IP address can be assigned to each system Ethernet port, thus providing a configuration with redundant Ethernet networks. v All service and configuration IP addresses associated with a clustered-system Ethernet port must be on the same subnet across all nodes. Each port can reside in its own subnet. v When the host object on the Storwize V7000 system side is created or recreated for an iSCSI host, you must log out of any existing sessions from that host and then log back in. Referenced from: http://pic.dhe.ibm.com/infocenter/storwize/ic/index.jsp Creating an iSCSI host on Storwize V7000 Create a host object on the Storwize V7000 system server that describes the iSCSI server target to which the volumes are to be mapped.