NexentaStor TM Target FC and Host Multipathing NexentaStor Release 3.1.x Target FC and Host Multipathing Copyright © 2011 Nexenta™ Systems, ALL RIGHTS RESERVED Notice: No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or stored in a database or retrieval system for any purpose, without the express written permission of Nexenta Systems (hereinafter referred to as “Nexenta”). Nexenta reserves the right to make changes to this document at any time without notice and assumes no responsibility for its use. Nexenta products and services only can be ordered under the terms and conditions of Nexenta Systems’ applicable agreements. All of the features described in this document may not be available currently. Refer to the latest product announcement or contact your local Nexenta Systems sales office for information on feature and product availability. 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Document revision number: 2 Date: August 26, 2011 2 Target FC and Host Multipathing Table of Contents 1 Introduction...............................................................................................................................5 1.1 Terminology.......................................................................................................................6 1.2 Installation .......................................................................................................................6 2 Examples of implementation....................................................................................................9 2.1 Setting up NexentaStor multipathing mode for Windows Server 2008 R2.......................9 2.2 Setting up NexentaStor multipathing on Linux-based OS..............................................19 3 References..............................................................................................................................21 4 Contact information.................................................................................................................23 4.1 Support request ..............................................................................................................23 4.2 Other resources...............................................................................................................24 3 Target FC and Host Multipathing 4 Target FC and Host Multipathing 1 Introduction Multipath I/O, or multipathing is a method to increase fault-tolerance and bandwidth performance. It provides multiple physical paths between the CPU in a computer system and its mass storage devices through the host bus adapters, controllers, switches, and bridge devices connecting them. Multipathing reduce the risk of a single point of error and let system administrator to set up multiple routes between the server and storage. A simple example would be a SCSI connected to two SCSI controllers on the same computer or a disk connected to two disk ports. If one of the component in this net work fails, the operating system can route I/O through the remaining transparently to the application, with no changes visible to the users, other than additional timeout. Fibre Chanel multipathing operates on low hardware level. Multipath software layers can leverage the usage of redundant paths to provide performance enhancing features, such as load balancing and traffic shaping. The following diagram represents the main idea of Fibre Chanel multipathing. 5 Target FC and Host Multipathing Currently, NexentaStor supports multipathing for Fibre Channel connections using supported SAS HBAs. With the help of Target FC plugin NexentaStor 3.0 can be turned to a fully compliant FC target (see section '3. References' for more info about NexentaStor plugins). 1.1 Terminology There are some basic terms, which need to be defined before starting multipathing configuration. Term Initiator Target Fibre Chanel 1.2 Definition Host, or client, that initiates a SCSI session, that is, sends a SCSI command. Endpoint that does not initiate sessions, but instead waits for initiators' commands and provides required input/output data transfers. The target usually provides to the initiators one or more LUNs. A gigabit-speed network technology primarily used for storage networking. Installation To start with configuring FC multipathing you need to install the corresponding scsitarget plugin (depending on your NexentaStor version). Run in NMC: nmc:/$ setup plugin install <PUGIN NAME> or install plugin via GUI: Settings → Appliance → Plugins: 6 Target FC and Host Multipathing 7 Target FC and Host Multipathing 8 Target FC and Host Multipathing 2 Examples of implementation. 2.1 Setting up NexentaStor multipathing mode for Windows Server 2008 R2. 1. Connect all the hardware. After installing FibreChannel HBAs in the system, the associated on the HBAs ports will automatically appear in the GUI. 2. On the Windows server, install appropriate management software for the Fibre Channel configuration (the software typically comes in a package with the FC HBAs). 3. • Enable MPIO feature on Windows Server: Open Server manager and choose 'Features'. 9 Target FC and Host Multipathing • In a pop-up window check 'Multipath I/O' 10 Target FC and Host Multipathing • Click on 'Install' on the next screen: 11 Target FC and Host Multipathing • After successful installation, the following screen appears. 12 Target FC and Host Multipathing • Later MPIO can be launched from 'Administrative Tools' 13 Target FC and Host Multipathing 4. Set up zvol on NexentaStor via NMC: nmc:/$ setup zvol create or via NMV (Data Management → SCSI target → Zvols →Create): 14 Target FC and Host Multipathing 5. Create Initiator group for more security: 15 Target FC and Host Multipathing 6. Create LUN Mappings (see 'NexentaStor SCSI Target' documentation for details): 16 Target FC and Host Multipathing 7. On the Windows side, run MPIO: press 'Start' and type “MPIO” in search tab. 8. Go to 'Discover Multi-Paths' - under Device Hardware ID. You should see 'NEXENTA COMSTAR' in the listing. 9. Press 'Add'. This operation requires reboot. 17 Target FC and Host Multipathing 10. After reboot you should see 'NEXENTA COMSTAR' in the list of devices 11. Open Administrative tools → Server management → Disk Management 12. Disks are available now – just need to be initialized. 18 Target FC and Host Multipathing 2.2 Setting up NexentaStor multipathing on Linux-based OS. With most of Linux-based OS you will have to deal with editing multipath.conf - multipath daemon configuration file. The following basic steps represent how to enable multipath mode for Red Hat Enterprise Linux 4: 1. Connect all the hardware. After plugging in Fibre Channel HBAs in the system, the associated on the HBAs ports will automatically appear in the GUI. 2. Follow the steps 4-6 from section 2.1.Setting up NexentaStor multipathing mode for Windows Server 2008 R2 to create a zvol and LUN mappings. 3. Make sure, that 'device-mapper-multipath' package is installed on the host. 4. multipath.conf need to be edited as follows: As far as all devices are blacklisted by default, the following lines are need to be commented out to enable multipathing: # devnode_blacklist { # devnode "*" # } You can change any of the 'defaults', such as user_friendly_name as per your own configuration needs. When it's done, save and exit. 5. Start multipathing daemon by running the following commands: # modprobe dm-multipath # service multipathd start 6. Check, if multipath daemons start on boot: # chkconfig multipathd on 19 Target FC and Host Multipathing 7. To list multipathed devices, run the command: # multipath -ll You should receive the output like: mpath0 (3600144f0ee48850000004c765d440001) dm-2 NEXENTA,COMSTAR [size=10G][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=1][enabled] \_ 1:0:0:0 sda 8:0 [active][ready] \_ round-robin 0 [prio=1][enabled] \_ 0:0:0:0 sdb 8:16 [active][ready] \_ round-robin 0 [prio=1][enabled] \_ 1:0:3:0 sdc 8:32 [active][ready] \_ round-robin 0 [prio=1][enabled] \_ 0:0:3:0 sdd 8:48 [active][ready] 8. The device can now be accessed (in the above example) using the path /dev/mapper/mpath0 20 Target FC and Host Multipathing 3 References • Target FC product web-page • Target 2.0 product web-page • Check Documentation 3.x and Documentation 2.x pages on www.nexenta.com for Target FC and Target 2.0 user manuals. F.A.Q. articles: • What does the term SCSI Target mean? • SCSI target: how to disable disk caching (NexentaStor v3.x) • Can NexentaStor act as an iSCSI or Fibre Channel target? 21 Target FC and Host Multipathing 22 Target FC and Host Multipathing 4 Contact information 4.1 Support request To contact support at Nexenta Systems, click on 'Support' in NMV as it's marked with red square on the screen bellow. or type the following NMC command: nmc:/$ support which will then prompt for a subject and message. 23 Target FC and Host Multipathing 4.2 Other resources For licensing questions, please email to [email protected] For more advanced questions related to the product, be sure to check our FAQ for the latest information. Nexenta Systems has various professional services offerings to assist with installing and managing the product. Training courses on high availability and other features of NexentaStor are also available. For service and training offerings, check our website at http://www.nexenta.com. About Nexenta Systems Founded in 2005 and privately held, Nexenta Systems, Inc., has developed NexentaStor™, the leading open storage enterprise class hardware independent storage solution and sponsors NexentaCore, an open source operating system that combines the high performance and reliability of OpenSolaris with the ease-ofuse and breadth of applications of Linux. Both solutions leverage the revolutionary file system ZFS. More information about Nexenta Systems, Inc. and free trials of the ZFS-based NexentaStor can be found at www.nexenta.com or call: (877) 862-7770. 24
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