- Explain the Pluggable Storage Architecture (PSA) layout
Skills and Abilities
- Install and Configure PSA plug-ins
- Understand different multipathing policy functionalities
- Perform command line configuration of multipathing options
- Change a multipath policy
- Configure Software iSCSI port binding
- vSphere Command-Line Interface Installation and Scripting Guide
- ESX Configuration Guide
- ESXi Configuration Guide
- Fibre Channel SAN Configuration Guide
- iSCSI SAN Configuration Guide
- Product Documentation
- vSphere Client
- vSphere CLI
Explain the Pluggable Storage Architecture (PSA) layout
What is Pluggable Storage Architecture (PSA) and Native Multipathing(NMP)?
Understanding VMware vSphere 4.1 PSA
Know the acronyms and understand the PSA. From Duncan Epping’s blog the acronyms below and a more in-depth information on each.
- PSA = Pluggable Storage Architecture
- NMP = Native Multipathing
- MPP = Multipathing Plugin (associates physical path with logical device)
- PSP = Path Selection Plugin (load-balancing)
- SATP = Storage Array Type Plugin (for failover) i.e. powerpath
- NMP “associates” a SATP with the set of paths from a given type of array.
- NMP “associates” a PSP with a logical device.
- NMP specifies a default PSP for every logical device based on the SATP associated with the physical paths for that device.
- NMP allows the default PSP for a device to be overridden.
Install and Configure PSA plug-ins
Understand different multipathing policy functionalities
Check out vStorage Multi Paths Options in vSphere
- Fixed will use the designate preferred path if configured and otherwise will use the first path discovered that works at system boot. A path is randomly selected when a failure occurs and the original path is selected when it comes back.
- Most recently uses the first working path at system boot. If this is unavailable, an alternative path is switched to and is used until the new path fails.
- Round Robin uses an automatic path selection that rotates and uses all available paths. It includes the ability to load balance across paths using active paths and is of most use on active/active array. In Active/passive arrays it will load between ports to the same storage processor. Not supported in MSCS environments.
- Fixed with array preference extends to fixed functionality to active/passive and ALUA mode arrays. VMW_PSP_FIXED_AP will select the preferred path according to array path preference and current path state.
Perform command line configuration of multipathing options
See the vSphere CLI Reference for full syntax and usage of the vicfg-mpath command.
Change a multipath policy
See the vSphere CLI Reference for full syntax and usage vicfg-mpath and esxcli commands.
Reminder, you must add –server <servername> as a connection option, otherwise the esxcli command will assume localhost, which will not work when running inside the vMA.
You use the esxcli command to set path policy like below, where VMW_PSP_xxx will either be Fixed, Fixed_AP, MRU, or RR
- esxcli <connection options> nmp device setpolicy –device naa.xxx –psp VMW_PSP_xxx
For more usage of this command check out Objective 6.4.
Configure Software iSCSI port binding (also referred to as multipathing)
See the vSphere CLI Reference for full syntax and usage of the esxcli command.
List available uplinks for use with iSCSI adapters
- esxcli swiscsi vmnic list –d <vmhba>
Connect iSCSI initiator to the VMkernel ports
- esxcli swiscsi nic add –n <port_name> –d <vmhba>
To disconnect iSCSI initiator from VMkernel ports
- esxcli swiscsi nic remove –n <port_name> –d <vmhba>
To list all sw iSCSI sessions at the adapter level or target level
- esxcli swisci session list –d <iscsi_adapter>
- esxcli swiscsi session list –d vmhba36
Remove iSCSI sw sessions
- esxcli swiscsi session remove –d