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Dynamic Multi-Pathing 7.4.1 Administrator's Guide - AIX
Last Published:
2019-02-01
Product(s):
InfoScale & Storage Foundation (7.4.1)
Platform: AIX
- Understanding DMP
- Setting up DMP to manage native devices
- About setting up DMP to manage native devices
- Displaying the native multi-pathing configuration
- Migrating LVM volume groups to DMP
- Migrating to DMP from EMC PowerPath
- Migrating to DMP from Hitachi Data Link Manager (HDLM)
- Migrating to DMP from IBM Multipath IO (MPIO) or MPIO path control module (PCM)
- Using Dynamic Multi-Pathing (DMP) devices with Oracle Automatic Storage Management (ASM)
- Enabling Dynamic Multi-Pathing (DMP) devices for use with Oracle Automatic Storage Management (ASM)
- Removing Dynamic Multi-Pathing (DMP) devices from the listing of Oracle Automatic Storage Management (ASM) disks
- Migrating Oracle Automatic Storage Management (ASM) disk groups on operating system devices to Dynamic Multi-Pathing (DMP) devices
- Adding DMP devices to an existing LVM volume group or creating a new LVM volume group
- Removing DMP support for native devices
- Dynamic Multi-Pathing for the Virtual I/O Server
- About Dynamic Multi-Pathing in a Virtual I/O server
- About the Volume Manager (VxVM) component in a Virtual I/O server
- Configuring Dynamic Multi-Pathing (DMP) on Virtual I/O server
- Configuring Dynamic Multi-Pathing (DMP) pseudo devices as virtual SCSI devices
- Extended attributes in VIO client for a virtual SCSI disk
- Administering DMP
- About enabling and disabling I/O for controllers and storage processors
- About displaying DMP database information
- Displaying the paths to a disk
- Setting customized names for DMP nodes
- Configuring DMP for SAN booting
- Administering the root volume group (rootvg) under DMP control
- Running the bosboot command when LVM rootvg is enabled for DMP
- Extending an LVM rootvg that is enabled for DMP
- Reducing the native rootvg that is enabled for DMP
- Mirroring the root volume group
- Removing the mirror for the root volume group (rootvg)
- Cloning a LVM rootvg that is enabled for DMP
- Cleaning up the alternate disk volume group when LVM rootvg is enabled for DMP
- Using mksysb when the root volume group is under DMP control
- Upgrading Dynamic Multi-Pathing and AIX on a DMP-enabled rootvg
- Using Storage Foundation in the logical partition (LPAR) with virtual SCSI devices
- Setting up DMP for vSCSI devices in the logical partition (LPAR)
- About disabling DMP for vSCSI devices in the logical partition (LPAR)
- Preparing to install or upgrade Storage Foundation with DMP disabled for vSCSI devices in the logical partition (LPAR)
- Disabling DMP multi-pathing for vSCSI devices in the logical partition (LPAR) after installation or upgrade
- Adding and removing DMP support for vSCSI devices for an array
- How DMP handles I/O for vSCSI devices
- Running alt_disk_install, alt_disk_copy and related commands on the OS device when DMP native support is enabled
- Administering DMP using the vxdmpadm utility
- Retrieving information about a DMP node
- Displaying consolidated information about the DMP nodes
- Displaying the members of a LUN group
- Displaying paths controlled by a DMP node, controller, enclosure, or array port
- Displaying information about controllers
- Displaying information about enclosures
- Displaying information about array ports
- User-friendly CLI outputs for ALUA arrays
- Displaying information about devices controlled by third-party drivers
- Displaying extended device attributes
- Suppressing or including devices from VxVM control
- Gathering and displaying I/O statistics
- Setting the attributes of the paths to an enclosure
- Displaying the redundancy level of a device or enclosure
- Specifying the minimum number of active paths
- Displaying the I/O policy
- Specifying the I/O policy
- Disabling I/O for paths, controllers, array ports, or DMP nodes
- Enabling I/O for paths, controllers, array ports, or DMP nodes
- Renaming an enclosure
- Configuring the response to I/O failures
- Configuring the I/O throttling mechanism
- Configuring Subpaths Failover Groups (SFG)
- Configuring Low Impact Path Probing (LIPP)
- Displaying recovery option values
- Configuring DMP path restoration policies
- Stopping the DMP path restoration thread
- Displaying the status of the DMP path restoration thread
- Configuring Array Policy Modules
- Administering disks
- About disk management
- Discovering and configuring newly added disk devices
- Partial device discovery
- About discovering disks and dynamically adding disk arrays
- About third-party driver coexistence
- How to administer the Device Discovery Layer
- Listing all the devices including iSCSI
- Listing all the Host Bus Adapters including iSCSI
- Listing the ports configured on a Host Bus Adapter
- Listing the targets configured from a Host Bus Adapter or a port
- Listing the devices configured from a Host Bus Adapter and target
- Getting or setting the iSCSI operational parameters
- Listing all supported disk arrays
- Excluding support for a disk array library
- Re-including support for an excluded disk array library
- Listing excluded disk arrays
- Listing disks claimed in the DISKS category
- Displaying details about an Array Support Library
- Adding unsupported disk arrays to the DISKS category
- Removing disks from the DISKS category
- Foreign devices
- Changing the disk device naming scheme
- Discovering the association between enclosure-based disk names and OS-based disk names
- Dynamic Reconfiguration of devices
- About online Dynamic Reconfiguration
- Reconfiguring a LUN online that is under DMP control using the Dynamic Reconfiguration tool
- Manually reconfiguring a LUN online that is under DMP control
- Overview of manually reconfiguring a LUN
- Manually removing LUNs dynamically from an existing target ID
- Manually adding new LUNs dynamically to a new target ID
- About detecting target ID reuse if the operating system device tree is not cleaned up
- Scanning an operating system device tree after adding or removing LUNs
- Manually cleaning up the operating system device tree after removing LUNs
- Manually replacing a host bus adapter online
- Changing the characteristics of a LUN from the array side
- Upgrading the array controller firmware online
- Event monitoring
- Performance monitoring and tuning
- About tuning Dynamic Multi-Pathing (DMP) with templates
- DMP tuning templates
- Example DMP tuning template
- Tuning a DMP host with a configuration attribute template
- Managing the DMP configuration files
- Resetting the DMP tunable parameters and attributes to the default values
- DMP tunable parameters and attributes that are supported for templates
- DMP tunable parameters
- DMP driver tunables
- Appendix A. DMP troubleshooting
- Appendix B. Reference
How DMP handles I/O for vSCSI devices
On the VIO client, DMP uses the Active/Standby array mode for the vSCSI devices. Each path to the vSCSI device is through a VIO server. One VIO server is Active and the other VIO servers are Standby. An Active/Standby array permits I/O through a single Active path, and keeps the other paths on standby. During failover, I/O is scheduled on one of the standby paths. After failback, I/Os are scheduled back onto the original Active path.
The following command shows the vSCSI enclosure:
# vxdmpadm listenclosure all ENCLR_NAME ENCLR_TYPE ENCLR_SNO STATUS ARRAY_TYPE LUN_COUNT FIRMWARE ======================================================================= ibm_vscsi0 IBM_VSCSI VSCSI CONNECTED VSCSI 9 -
The following command shows the I/O policy for the vSCSI enclosure:
# vxdmpadm getattr enclosure ibm_vscsi0 iopolicy ENCLR_NAME DEFAULT CURRENT ============================================ ibm_vscsi0 Single-Active Single-Active
For vSCSI devices, DMP balances the load between the VIO servers, instead of balancing the I/O on paths. By default, the iopolicy attribute of the vSCSI array is set to lunbalance. When lunbalance is set, the vSCSI LUNs are distributed so that the I/O load is shared across the VIO servers. For example, if you have 10 LUNs and 2 VIO servers, 5 of them are configured so that VIO Server 1 is Active and VIO Server 2 is Standby. The other 5 are configured so that the VIO Server 2 is Active and VIO Server 1 is Standby. To turn off load sharing across VIO servers, set the iopolicy attribute to nolunbalance.
DMP dynamically balances the I/O load across LUNs. When you add or remove disks or paths in the VIO client, the load is rebalanced. Temporary failures like enabling or disabling paths or controllers do not cause the I/O load across LUNs to be rebalanced.