IBM(R) Total Storage Multipath Subsystem Device Driver Version 1.6.0.1-8.1 README for Linux 2.4 ------------------------------------------------------------------------------- CONTENTS 1.0 About this README file 1.1 Who should read this README file 1.2 How to get help 2.0 Prerequisites for SDD 3.0 SDD Change History 3.1 Defects Fixed 3.1.1 Common 3.1.2 ESS/DS8000/DS6000 Defects 3.1.3 SVC Defects 3.1.4 SVCCISCO Defects 3.2 New Features 3.3 Feature Details 3.4 Known Issues 3.5 Correction to User's Guide 4.0 User License Agreement for IBM Device Drivers 5.0 Notices 6.0 Trademarks and Service Marks ------------------------------------------------------------------------------- 1.0 About this README file Welcome to IBM Multipathing Subsystem Device Driver (SDD). This README file contains the most recent information about the IBM Multipathing Subsystem Device Driver, Version 1.6.0.1-8.1 for Linux. IBM recommends that you go to the following Web site to get the most current information about this release of SDD: http://www.ibm.com/servers/storage/support/software/sdd.html You should carefully review the following information available through the website: 1. The most current README file. This will contain corrections to this readme file, corrections to the SDD User's Guide, and other documentation updates discovered since this copy of the README was prepared. 2. The Multipath SDD Users' Guide. Because SDD can be installed in so many different environments / configurations, detailed information about each environment is placed in the appropriate chapter of the Multipath SDD Users Guide. The 'Summary of Changes' section of the SDD Users' Guide can help you quickly determine if the latest changes affect you. 3. The Flashes. As we become aware of any information that is likely to impact a broad set of our customers, Flashes are prepared and posted on this site. You should review this section periodocally to see any new Flashes that have been posted since your last review. For prerequisites information, be sure to look in the Multipath SDD User's Guide as well as the prerequisites section of this readme file for the latest updates. 1.1 Who should read this README file This README file is intended for storage administrators, system programmers, and performance and capacity analysts. The information in this file only applies to customers who run: 1. ESS, DS8000, DS6000, SAN Volume Controller, or SAN Volume Controller for Cisco MDS 9000 2. ESS and SAN Volume Controller 3. ESS and SAN Volume Controller for Cisco MDS 9000 1.2 How to get help Go to the following Web site for SDD technical support and for the most current SDD documentation and support information: http://www.ibm.com/servers/storage/support/software/sdd.html Go to the following Web site for the IBM ESS Open Systems support: http://www.storage.ibm.com/hardsoft/products/ess/supserver.htm Go to the following Web site for IBM TotalStorage DS8000 support: http://www-1.ibm.com/servers/storage/disk/ds8000/index.html Go to the following Web site for IBM TotalStorage DS6000 support: http://www-1.ibm.com/servers/storage/disk/ds6000/index.html Go to the following Web site for IBM TotalStorage SAN Volume Controller support: http://www.ibm.com/servers/storage/support/virtual/2145.html Go to the following Web site for IBM TotalStorage SAN Volume Controller for Cisco MDS 9000 support: http://www.ibm.com/servers/storage/support/virtual/2062-2300.html Call one of the following numbers to obtain nontechnical or administrative support, such as hardware and software orders, hardware maintenance, services contract of entitlement, and invoices: .For commercial or state and local support operations: 1-877-426-6006 (Listen to the voice prompts) .For business partner support operations: 1-800-426-9990 .For federal government support operations: 1-800-333-6705 ------------------------------------------------------------------------------- 2.0 Prerequisites for SDD One of the following combinations of a Linux distribution and associated vendor compiled binary kernel packages: SuSE SLES8 / UnitedLinux 1.0 (x86) with one of the following kernels: k_smp-2.4.21-138 k_smp-2.4.21-169 k_smp-2.4.21-190 k_smp-2.4.21-198 k_smp-2.4.21-215 k_smp-2.4.21-226 k_smp-2.4.21-231 k_smp-2.4.21-241 k_smp-2.4.21-251 k_smp-2.4.21-261 k_smp-2.4.21-266 k_smp-2.4.21-273 k_smp-2.4.21-278 k_smp-2.4.21-281 k_smp-2.4.21-286 k_smp-2.4.21-292 k_smp-2.4.21-295 * SuSE SLES8 (ppc64) with one of the following kernels: kernel-ppc64-2.4.21-111 kernel-ppc64-2.4.21-147 kernel-ppc64-2.4.21-154 kernel-ppc64-2.4.21-155 kernel-ppc64-2.4.21-215 kernel-ppc64-2.4.21-223 kernel-ppc64-2.4.21-231 kernel-ppc64-2.4.21-241 kernel-ppc64-2.4.21-251 kernel-ppc64-2.4.21-261 kernel-ppc64-2.4.21-266 kernel-ppc64-2.4.21-273 kernel-ppc64-2.4.21-278 kernel-ppc64-2.4.21-281 kernel-ppc64-2.4.21-292 kernel-ppc64-2.4.21-295 * SuSE SLES8 (ia64) with one of the following kernels: k_itanium2-smp-2.4.21-215 k_itanium2-smp-2.4.21-231 k_itanium2-smp-2.4.21-241 k_itanium2-smp-2.4.21-248 k_itanium2-smp-2.4.21-251 k_itanium2-smp-2.4.21-261 k_itanium2-smp-2.4.21-266 k_itanium2-smp-2.4.21-273 k_itanium2-smp-2.4.21-278 k_itanium2-smp-2.4.21-286 k_itanium2-smp-2.4.21-292 k_itanium2-smp-2.4.21-295 * * Newly supported in this release ------------------------------------------------------------------------------- 3.0 SDD Change History =============================================================================== 3.1 Defects Fixed 3.1.1 Common 1.6.0.1-8 o 3473 Ensure that the command-line 'debug' options, i.e. 'cfgvpath debug', 'rmvpath debug', and 'addpaths debug', have consistent descriptions and behavior, printing the debug messages to stdout. o 3475 Complete fix to allow Linux HDIO_GETGEO ioctl calls on vpath partitions. o 3450 Fix problems in path state transition. o 3461 Allow Linux HDIO_GETGEO ioctl calls on vpath partitions. 1.6.0.1-6 o 3340 Fix 'datapath query wwpn' to handle listing more than ten adapter wwpns. o 3341 Fix problem where /etc/vpath.conf file was not updated when removing a vpath with debugging enabled, i.e. 'rmvpath debug'. 1.6.0.1-3 o 3156 Fix potential hang during sdd.log trace collection. 1.6.0.1-1 o 3089 Fix problems with cfgvpath 1.6.0.0-15 o 2835 Fix cfgvpath handling of the comment flag for vpath.conf. o 2840 Fix rmvpath to correctly comment out entries. o 2752 Improve sequential IO performance (opensfs defect 8891). o 2788 Fix cfgvpath crash (PMR 06708). o 2812 Fix adapter counts during addpath on open devices o 2819 Fix SFS performance on Standby controller: (opensfs defect 9248). o 117920 SDD start error. o 2632 Enable non-root user to open vpath device. o 2618 DB2 users cannot use vpath device. o 2559 Fix for raw vpath error retry I/O hang. 3.1.2 ESS/DS8000/DS6000 Defects None 3.1.3 SVC Defects None 3.1.4 SVCCISCO Defects None 3.1.4 SANFS Defects None =============================================================================== 3.2 New Features 1.6.0.1-3 o PCR 2886 Add "-l" option to datapath query device command to indicate paths to a non-preferred controller. o Redhat and Red Flag: Not allow rpm upgrade or removal while SDD is in use (can be overridden). 1.6.0.0-15 o Turn on debug tracing by default. o Separated out the optimized sequential policy from the optimized policy, and added a round robin sequential policy. o Enable non-root user to open vpath device. o Added support for DS8000 (2107) and DS6000 (1750) devices. =============================================================================== 3.3 Feature Details 1.6.0.1-3 o PCR 2886 A new feature has been introduced to datapath to aid users to in verifying their SAN configurations in a controller environment (such as with the SAN Volume Controller). The datapath query device command now has a new option '-l' to display paths to non-preferred controllers. For example, if users have 4 paths per SDD vpath device and they would like to configure a equal distribution between preferred controller and non-preferred controller, they will configure their environment with 2 paths from a preferred controller and another 2 paths from a non-preferred one. This feature will help users to verify their configuration by indicating which path is from the non-preferred controller before the device starts operation. For 'datapath query device', a new option, '-l', is added to mark the non-preferred paths with an asterisk. This option can be used in addition to the existing datapath query device command. For example: - datapath query device -l - datapath query device -l In the datapath query device output, the non-preferred paths are marked with a *, as below: DEV#: 35 DEVICE NAME: vpathbd TYPE: 2145 POLICY: Optimized Sequential SERIAL: 60050768018b800a800000000000008c LUN IDENTIFIER: 60050768018b800a800000000000008c ============================================================================ Path# Adapter/Hard Disk State Mode Select Errors 0* Host3Channel0/sdcu CLOSE NORMAL 0 0 1 Host3Channel0/sddc CLOSE NORMAL 22985 0 2 Host2Channel0/sds CLOSE NORMAL 26398 0 3* Host2Channel0/sdk CLOSE NORMAL 0 0 o Redhat and Red Flag: Not allow rpm upgrade or removal while SDD is in use. This can be overridden with a --nopre and --nopreun flag to rpm, but since SUSE does not support these flgas the feature is not available in SuSE (--noscripts prevents required post conditions from running as well, so is not an option). 1.6.0.0-15 o Tracing is now turned on by default for SDD. The SDD driver logs are saved to /var/log/sdd.log and the sddsrv daemon logs are saved to /var/log/sddsrv.log. o As part of the new performance improvement, we separated out an optimized sequential policy from the optimized policy, and added a round robin sequential policy. The optimized sequential policy is now the default policy of linux. Both the sequential policies base the path selection on whether the IO is sequential, and if not fall though to use the exising optimized (load balanced) or round robin policies. Highly sequential IO can have a significant performance improvement, and non sequential IO should perform the same as without the sequential policy in place. o Non-root users can now open a vpath device. Before, only root users would have this privilege, but with raised capabilities in the OS non-root users can do the same. o Added support for DS8000 (2107) and DS6000 (1750) devices. =============================================================================== 3.4 Known Issues o Kernel offlines scsi_device erroneously During I/O load, the kernel may decide to offline a scsi_device, e.g. /dev/sd[X], thus disabling an SDD path entirely; all I/O to the underlying sd device will fail. When this happens, a message should appear in /var/log/messages that resembles: kernel: scsi: device set offline - not ready or command retry failed after bus reset: host 0 channel 0 id 0 lun 4 Once the scsi_device is offlined by the kernel, the kernel will not put the scsi_device back online again automatically, even if the path is ok. Unfortunately, this scenario can occur under good path I/O load when the path, i.e. scsi_device, is still usable because the I/O load is greater than the storage can complete within the SCSI mid-layer timeout period. If the I/O time-outs continue, it is possible that the SDD vpath device could go offline due to IBM storage not being able to complete IOs within the SCSI mid-layer time-out time. The only way to bring the scsi_device back online is to reload the HBA driver. Please be sure to stop SDD before reloading the HBA driver. The SCSI mid-layer time-out could be increased to attempt to workaround thisissue. o Hot add of LUNs is not supported on any distributions at this time. If devices are added on the SAN, it is recommended that the SDD driver and HBA driver be unloaded and reloaded. o The adapter status may be different than the device status, although everything is functioning normally. o For Linux systems using Qlogic adapters that are attached to DS6000 systems that will be performing PPRC or Flash Copy type functions, IO time-out may occur when the PPRC or Flash copy function occurs on the DS6000. To workaround this issue, Qlogic driver's queue full retry count can be increased by adding the following option to /etc/modprobe.conf or /etc/modules.conf: 'option qla2300/qla2xxx qfull_retry_count=32' o For Emulex adapters running in RHEL3 U5, an issue was found where LUN 0 may be missing from the list of available LUNs. A workaround for this issue is to add the following option to /etc/modules.conf: `options lpfc lpfc_inq_pqb_filter=0x1` =============================================================================== 3.5 Correction to User's Guide o Change in the path state transition During path open or sddsrv path probing, SDD will no longer skip CLOSE OFFLINE paths. Their state will be changed to INVALID if open fails or DEAD if open succeeds and mode remains in OFFLINE. CLOSED_DEAD path will stay in CLOSED_DEAD during vpath open, instead of changing into INVALID state. ------------------------------------------------------------------------------- 4.0 User License Agreement for IBM Device Drivers See the LICENSE file located in /opt/IBMsdd. ------------------------------------------------------------------------------- 5.0 Notices This information was developed for products and services offered in the U.S.A. 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