iSCSI Cookbook

Description

This cookbook provides the ability to configure Open-iSCSI for Enterprise Linux based systems. The default attributes reflect original research and recommendations gathered from Dell, Equallogic, and RedHat.

Here is a link to my own whitepaper in blog form, discussing the configuration and tuning of Open-iSCSI with this cookbook, as supplementary documentation. Here is a list of recommended source documentation in addition to the linked blog post.

• Red Hat KB 2877
• Dell PowerEdge Systems Red Hat Enterprise Linux 5.4 Install Notes (dead link)
• Red Hat Linux v5.x Software iSCSI Initiator Configuration and tuning Guide (dead link)
• Open-iSCSI documentation

Requirements

Required Cookbooks

• multipath
• sysctl

Recommended Cookbooks

• dbench

Attributes

iscsid.conf

• iscsi (namespace)
  • ['session']['timeo']['replacement_timeout'] Time to wait before failing SCSI commands back to the application, default 15
  • ['conn0']['timeo']['noop_out_interval'] Interval to wait before sending a ping, default 5
  • ['conn0']['timeo']['noop_out_timeout'] Time to wait for a NOP-out before failing the connection, default 5
  • ['session']['initial_login_retry_max'] Initial number of login tries, default 12
  • ['session']['cmds_max'] How many commands the session will queue, default 1024
  • ['session']['queue_depth'] Device queue depth, default 128
  • ['session']['iscsi']['fastabort'] IET targets need Yes, Equallogic needs set to No. Default is Yes

udev

• iscsi.udev (namespace)
  • ['interfaces'] Array of ethernet devices to apply ethtool options via udev. Default empty.
  • ['ethtool_opts'] Turn on, or off, certain features on iSCSI ethernet devices. Default flow control on, autonegotiate off, Generic Recieve offload off.
  • [reload_command'] platform version specific command to reload udev rules.

sysctl.params

• sysctl.params.net.ipv4 (namespace)
  • ['conf']['all']['arp_ignore'] Modes of ARP replies. Default 1, reply only if local IP address.
  • ['conf']['all']['arp_announce'] Modes of ARP announcement. Default 2, use the best lcoal address.
  • ['ipv4']['netfilter']['ip_conntrack_tcp_be_liberal'] 1 Disables TCP window tracking, default 1 on RHEL5.

Usage

Default recipe

Set role specific overrides, and add recipe['iscsi'] to runlist

Example iSCSI role for an Equallogic storage array

name 'iscsi'
description 'Installs and configures Open-iSCSI for EQL. Installs dm-multipath.  Configures sysctl.'
override_attributes 'iscsi' => {
  'session' => {
    'iscsi' => {
      'fastabort' => 'No'
  }
},
run_list 'recipe[iscsi]', 'recipe[multipath]', 'recipe[dbench]'

Example iSCSI role for an IET storage array

name 'iscsi'
description 'Installs and configures Open-iSCSI for IET. Installs dm-multipath.  Configures sysctl.'
override_attributes 'iscsi' => {
  'session' => {
    'iscsi' => {
      'fastabort' => 'Yes'
  }
},
run_list 'recipe[iscsi]', 'recipe[multipath]', 'recipe[dbench]'

rescan-scsi-bus recipe

Simply include_recipe 'iscsi::rescan-scsi-bus' to drop off Kurt Garloff's handy rescan-scsi-bus script. This has nothing to do with iSCSI, other than it may come in handy to rescan the SCSI bus when you target a new LUN.

This recipe only drops off the script in /usr/local/bin, the recipe does not execute anything.

License and Author

Copyright 2010-2012, Eric G. Wolfe

Licensed under the Apache License, Version 2.0 (the 'License'); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an 'AS IS' BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.