Hitachi Dynamic Link Manager Software Users Guide for AIX (7.6)
Table Of Contents
- User Guide for AIX®
- Contents
- Preface
- Overview of HDLM
- HDLM Functions
- Devices Managed by HDLM
- System Configuration
- LU Configuration
- Program Configuration
- Position of the HDLM Driver and hdisk
- Distributing a Load Using Load Balancing
- Performing Failovers and Failbacks Using Path Switching
- Monitoring intermittent errors (functionality when automatic failback is used)
- Detecting errors by using path health checking
- Distributing a Load by Using the Dynamic I/O Path Control Function
- Error management
- Collecting Audit Log Data
- Integrated HDLM management using Global Link Manager
- Cluster support
- Creating an HDLM Environment
- HDLM System Requirements
- Flow for Creating an HDLM Environment
- Types of HDLM Installation
- Notes on Creating an HDLM Environment
- Installing HDLM
- Available Installation Methods
- Preparations for a New Installation of HDLM
- Performing a New Installation of HDLM
- Preparations for an Upgrade Installation or Re-installation of HDLM
- Performing an Upgrade Installation or Re-installation of HDLM
- Migrating from HDLM Version 5.8.1 or Earlier to Version 5.9 or Later
- Installing HDLM in a PowerHA 6.1 Environment
- Installing HDLM in a PowerHA 7.1 Environment
- Performing an Unattended Installation of HDLM
- Checking the Path Configuration
- Setting up HDLM
- Setting up Integrated Traces
- Notes on Using the Hitachi Network Objectplaza Trace Library
- Displaying the Hitachi Network Objectplaza Trace Library setup menu
- Changing the Size of Integrated Trace Files
- Changing the Number of Integrated Trace Files
- Changing the Buffer Size Per Monitoring Interval Duration
- Adjusting the Number of Messages to be Output Per Monitoring Interval
- Finishing the Hitachi Network Objectplaza Trace Library Settings
- Applying the Hitachi Network Objectplaza Trace Library Settings
- About the Reservation Policy
- Settings for Using PowerHA
- Settings for Using GPFS
- Settings for Using Oracle RAC 10g or Oracle RAC 11g
- Settings for Using VCS
- Removing HDLM
- HDLM Operation
- Notes on Using HDLM
- Displaying Path Information
- When a Path Error Is Detected
- Storage System
- Notes on Shutting Down a Host
- Notes on Errors in a Host
- Notes on Enabling Both Primary and Secondary Volumes to Be Viewed From the Same Server
- Notes on an LVM Mirror Configuration
- Notes on When the OS Functionality in Not Available in a Boot Disk Environment
- Notes on Replicating a System
- HDLM Operations Using Commands
- Notes on Using Commands
- Viewing Path Information
- Changing the Status of Paths
- Viewing LU Information
- Displaying the Correspondences Between hdisks, OS Management Path IDs, and LDEVs
- Initializing Statistical Information for Paths
- Viewing and Setting Up the Operating Environment
- Viewing License Information
- Updating the License
- Viewing HDLM Version Information
- Viewing HDLM Component Information
- Starting and Stopping the HDLM Manager
- HDLM Resident Processes
- Changing the Configuration of the HDLM Operating Environment
- Notes on Using HDLM
- Troubleshooting
- Command Reference
- Overview of the HDLM Command dlnkmgr
- clear (Returns the Path Statistics to the Initial Value)
- help (Displays the Operation Format)
- offline (Places Paths Offline)
- online (Places Paths Online)
- set (Sets Up the Operating Environment)
- view (Displays Information)
- add (Adds a Path Dynamically)
- delete (Deletes a Path Dynamically)
- Utility Reference
- Overview of the Utilities
- DLMgetras Utility for Collecting HDLM Error Information
- dlmchpdattr Utility for Changing HDLM Default Settings
- dlmgetrasinst Utility for Collecting HDLM Installation Error Information
- dlminstcomp Utility for HDLM Component Installation
- dlmmigsts Utility for Assisting HDLM Migration
- dlmodmset Utility for Setting the HDLM Execution Environment ODM
- dlmpostrestore Utility for HDLM Restoration Support
- dlmpr Utility for Clearing HDLM Persistent Reservation
- dlmpremkcd Utility for Preparing for a System Backup
- dlmpreremove Utility for Executed Before Removing HDLM
- dlmrmdev Utility for Deleting HDLM Drivers
- dlmrmprshkey Utility for Clearing HDLM Persistent Reservation (Shared-Host Methodology)
- installhdlm Utility for Installing HDLM
- installux.sh Utility for HDLM Common Installer
- Messages
- Before Viewing the List of Messages
- KAPL01001 to KAPL02000
- KAPL03001 to KAPL04000
- KAPL04001 to KAPL05000
- KAPL05001 to KAPL06000
- KAPL06001 to KAPL07000
- KAPL07001 to KAPL08000
- KAPL08001 to KAPL09000
- KAPL09001 to KAPL10000
- KAPL10001 to KAPL11000
- KAPL11001 to KAPL12000
- KAPL13001 to KAPL14000
- KAPL15001 to KAPL16000
- Return Codes for Hitachi Command Suite Common Agent Component
- Functional Differences Between Versions of HDLM
- Differences Between HDLM Version 5.9 or Later and Version 5.8.1 or Earlier
- Add-in HDLM Driver Module
- Simplifying the HDLM Environment Configuration and Operation Procedures by Changes to the Logical Device Files
- Changing the HDLM Environment Configuration and Operation Procedures by Changes to the Logical Device Files
- Migrating Reservation Control Settings
- Support for a Boot Disk Environment
- About Settings when Upgrading the OS
- Changing a Virtual I/O Server's Method of Recognizing Virtual SCSI Disks
- Acronyms and abbreviations
- Glossary
- Index
If the data is not sequential, these algorithms select the path to be used
each time an I/O request is issued.
¢
Extended Round Robin
The paths are simply is selected in order from among all the
connected paths.
¢
Extended Least I/Os
The path that has the least number of I/Os being processed is
selected from among all the connected paths.
¢
Extended Least Blocks
The path that has the least number of I/O blocks being processed is
selected from among all the connected paths.
The following table lists and describes the features of the load balancing
algorithms.
Table 2-4 Features of the Load Balancing Algorithms
Algorithm type Algorithm features
•
Round Robin
#
• Least I/Os
• Least Blocks
These types of algorithms are most effective when a lot of
discontinuous, non-sequential I/Os are issued.
• Extended Round
Robin
• Extended Least I/Os
• Extended Least
Blocks
If there is a read request for I/O data that is sequential with
the data of the I/O that was issued immediately beforehand,
an improvement in reading speed can be expected due to the
storage system cache functionality. These types of
algorithms are most effective when many continuous I/Os
are issued (the I/O data is sequential).
#
Some I/O operations managed by HDLM can be distributed across all
paths, and some cannot. Thus, you should be aware that even if you
specify the Round Robin algorithm, I/O operations cannot always be
allocated uniformly across all paths.
By default, the Extended Least I/Os algorithm is set when HDLM is first
installed. When an upgrade installation of HDLM is performed, the existing
setting is inherited.
Select the load balancing algorithm most suitable for the data access patterns
in your system environment. If there are no recognizable data access
patterns, we recommend applying the Extended Least I/Os algorithm.
You can specify the load balancing function by the dlnkmgr command's set
operation. For details on the set operation, see
set (Sets Up the Operating
Environment) on page 6-17.
HDLM Functions
2-13
Hitachi Dynamic Link Manager User Guide for AIX
®