If your server has two HBA cards connected to EMC SAN storage device, you can implement load-balancing, and fail-over on the HBA cards using the EMC PowerPath software.
Powermt management utility helps you manage I/O paths from the server to the EMC storage device. In this article, let us discuss how to use powermt command with practical examples.
1. powermt display – Display High Level HBA I/O Paths
powermt display command (without any arguments), displays the available HBAs and their current status. The following examples, shows that there are 2 HBAs connected to the server, both the HBAs are in active condition with 2 I/O path’s each. qla2xxx indicates that it is using the Q-Logic HBA card.
This also indicates that the connected EMC device is CLARiiON, as it displays a value for “CLARiiON logical device count” as 1.
C:\Program Files\EMC\PowerPath> powermt display
Symmetrix logical device count=0
CLARiiON logical device count=1
Hitachi logical device count=0
Invista logical device count=0
HP xp logical device count=0
Ess logical device count=0
HP HSx logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— I/O Paths —– —— Stats ——
### HW Path Summary Total Dead IO/Sec Q-IOs Errors
==============================================================================
1 qla2xxx optimal 2 0 – 0 0
2 qla2xxx optimal 2 0 – 0 0
2. powermt display dev=all – Display All Attached LUNs
This is the most frequently used powermt command, which will display all the attached logical devices to the server.
C:\Program Files\EMC\PowerPath> powermt display dev=all
Pseudo name=emcpowera
CLARiiON ID=AAA00000000000 [dev-server]
Logical device ID=1111111111111111111 [LUN 1]
state=alive; policy=CLAROpt; priority=0; queued-IOs=0
Owner: default=SP B, current=SP B Array failover mode: 1
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sdd SP A4 active alive 0 0
1 qla2xxx sde SP B4 active alive 0 0
2 qla2xxx sdf SP A5 active alive 0 0
2 qla2xxx sdg SP B5 active alive 0 0
Pseudo name=emcpowerb
CLARiiON ID=AAA00000000000 [dev-server]
Logical device ID=2111111111111111111 [LUN 2]
state=alive; policy=CLAROpt; priority=0; queued-IOs=0
Owner: default=SP A, current=SP A Array failover mode: 1
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sdh SP A4 active alive 0 0
1 qla2xxx sdi SP B4 active alive 0 0
2 qla2xxx sdj SP A5 active alive 0 0
2 qla2xxx sdk SP B5 active alive 0 0
The above indicates that there are two LUNs attached to the dev-server with 4 I/O paths from the server to the SAN storage device.
The above command output indicates the following:
Pseudo name=emcpowera – The device name that can be used by the server. For example, /dev/emcpowera.
CLARiiON ID=AAA00000000000 [dev-server] – EMC CLARiiON CX3 serial number and the server name.
Logical device ID=11111111 [LUN 1] – LUN number. For example, LUN 1.
state=alive; policy=CLAROpt; – This displays that this particular LUN is valid and using the CLAROpt policy.
Owner: default=SP B, current=SP B – This indicates that the default (and current) owner for this LUN is storage processor SP B.
3. powermt display dev=emcpowera – Display specific LUN
When there are multiple LUNs connected to a server, you might want to view information about a specific LUN by providing the logical name of the LUN as shown below.
C:\Program Files\EMC\PowerPath> powermt display dev=emcpowera
Pseudo name=emcpowera
CLARiiON ID=AAA00000000000 [dev-server]
Logical device ID=1111111111111111111 [LUN 1]
state=alive; policy=CLAROpt; priority=0; queued-IOs=0
Owner: default=SP B, current=SP B Array failover mode: 1
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sdd SP A4 active alive 0 0
1 qla2xxx sde SP B4 active alive 0 0
2 qla2xxx sdf SP A5 active alive 0 0
2 qla2xxx sdg SP B5 active alive 0 0
If the device is not available, you’ll get a “Bad dev value” as shown below.
C:\Program Files\EMC\PowerPath>powermt display dev=emcpowerc
Bad dev value emcpowerc, or not under Powerpath control.
4. powermt check_registration – Display PowerPath Registration Key / Status
If you’ve lost the PowerPath registration key that you’ve used during the EMC PowerPath installation, you can retrieve it using the following command.
C:\Program Files\EMC\PowerPath> powermt check_registration
Key AAAA-BBBB-CCCC-DDDD-EEEE-FFFF
Product: PowerPath
Capabilities: All
5. powermt display options – Display EMC PowerPath Options
Displays the high level EMC SAN array options as shown below.
C:\Program Files\EMC\PowerPath> powermt display options
Default storage system class: all
Show CLARiiON LUN names: true
Path Latency Monitor: Off
Path Latency Threshold: 0 Sec.
Storage
System Class Attributes
———— ———-
Symmetrix periodic autorestore = on
status = managed
CLARiiON periodic autorestore = on
status = managed
Hitachi periodic autorestore = on
status = managed
Invista periodic autorestore = on
status = managed
HP xp periodic autorestore = on
status = managed
Ess periodic autorestore = on
status = managed
HP HSx periodic autorestore = on
status = managed
6. powermt display hba_mode – Display PowerPath HBA Mode
This is similar to #1, but displays whether hba is enabled or not, as shown in the last column of the output.
7. powermt display path – Display available I/O Paths.
This displays all available path for your SAN device.
C:\Program Files\EMC\PowerPath> powermt display paths
Symmetrix logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
CLARiiON logical device count=1
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
1 qla2xxx AAA00000000000 SP A4 1 0
1 qla2xxx AAA00000000000 SP B4 1 0
2 qla2xxx AAA00000000000 SP A5 1 0
2 qla2xxx AAA00000000000 SP B5 1 0
Hitachi logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
Invista logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
HP xp logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
Ess logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
HP HSx logical device count=0
==============================================================================
—– Host Bus Adapters ——— —— Storage System —– – I/O Paths –
### HW Path ID Interface Total Dead
==============================================================================
8. powermt displays port_mode – Display Port Status
Displays the status of the individual ports on the HBA. i.e Whether the port is enabled or not.
C:\Program Files\EMC\PowerPath> powermt display port_mode
Storage class = Symmetrix
==============================================================================
———– Storage System ————— — I/O Paths — — Stats —
ID Interface Wt_Q Total Dead Q-IOs Mode
==============================================================================
Storage class = CLARiiON
==============================================================================
———– Storage System ————— — I/O Paths — — Stats —
ID Interface Wt_Q Total Dead Q-IOs Mode
==============================================================================
AAA00000000000 SP A4 256 1 0 0 Enabled
AAA00000000000 SP B4 256 1 0 0 Enabled
AAA00000000000 SP A5 256 1 0 0 Enabled
AAA00000000000 SP B5 256 1 0 0 Enabled
9. powermt version – Display EMC PowerPath Version
How to identify the version number of EMC PowerPath software?
C:\Program Files\EMC\PowerPath> powermt version
EMC powermt for PowerPath (c) Version 5.3 (build 185)
10. powermt check – Check the I/O Paths
If you have made changes to the HBA’s, or I/O paths, just execute powermt check, to take appropriate action. For example, if you have manually removed an I/O path, check command will detect a dead path and remove it from the EMC path list.
C:\Program Files\EMC\PowerPath> powermt check
Warning: storage_system I/O path path_name is dead.
Do you want to remove it (y/n/a/q)?
Note: If you want powermt to automatically remove all dead paths, without any confirmation, execute “powermt check force”.
11. powermt set mode hba – Forcefully set the mode for a specific HBA
You can change the mode of a specific HBA to either standby or active using this command. Following example, changes HBA #1′s mode from active to standby.
C:\Program Files\EMC\PowerPath> powermt set mode=standby hba=1
After the above command, you can see the mode for HBA#1 changed to standby, as shown below.
C:\Program Files\EMC\PowerPath> powermt display dev=all
Pseudo name=emcpowera
CLARiiON ID=AAA00000000000 [dev-server]
Logical device ID=1111111111111111111 [LUN 1]
state=alive; policy=CLAROpt; priority=0; queued-IOs=0
Owner: default=SP B, current=SP B Array failover mode: 1
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sdd SP A4 standby alive 0 0
1 qla2xxx sde SP B4 standby alive 0 0
2 qla2xxx sdf SP A5 active alive 0 0
2 qla2xxx sdg SP B5 active alive 0 0
Note: Path mode can also be “unlic” indicating that you’ve not registered the PowerPath with proper License key.
Note: Some powermt commands (for example, powermt set port_disable), is restricted to certain platform and storage type — On AIX and Solaris, only Fibre channel is supported. On HP-UX, only iSCSI and Fibre are supported. On Linux, Only iSCSI (HBAs) and Fibre are supported.
12. powermt remove – Delete an I/O Path
Use this command to remove any specific I/O path (or) a whole device.
The following example has 4 I/O Paths.
C:\Program Files\EMC\PowerPath> powermt display dev=all
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sdd SP A4 standby alive 0 0
1 qla2xxx sde SP B4 standby alive 0 0
2 qla2xxx sdf SP A5 active alive 0 0
2 qla2xxx sdg SP B5 active alive 0 0
To remove I/O Path sdd, execute the following powermt remove command.
C:\Program Files\EMC\PowerPath> powermt remove dev=sdd
C:\Program Files\EMC\PowerPath> powermt display dev=all
==============================================================================
—————- Host ————— – Stor – — I/O Path – — Stats —
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
1 qla2xxx sde SP B4 standby alive 0 0
2 qla2xxx sdf SP A5 active alive 0 0
2 qla2xxx sdg SP B5 active alive 0 0
Following will remove all I/O Path for a particular device. i.e To remove /dev/emcpowera, do the following. If the /dev/emcpowera is mounted and used by some program, following command will not work.
C:\Program Files\EMC\PowerPath> powermt remove dev=emcpowera
13. powermt config – Configure PowerPath
This command checks for available EMC SAN logical devices and add those to PowerPath configuration list. Powermt config command, sets some of the options to it’s default values. For example, write throttling = off, HBA mode = active, CLARiiON policy = CLAROpt, etc.
Possible EMC SAN LUN policy values are: Adaptive, BasicFailover, CLAROpt, LeastBlocks, LeastIos, NoRedirect, Request, RoundRobin, StreamIO, or SymmOpt.
After you execute the powermt config, if you don’t like any of the default values, you should change it accordingly.
C:\Program Files\EMC\PowerPath> powermt config
14. powermt restore – Make Dead I/O Path Alive
If you have dead I/O paths, and if you’ve done something to fix the issue, you can request PowerPath to re-check the paths and mark it as active using powermt restore command.
When you execute powermt restore, it does an I/O path check. If a previously dead path is alive, it will be marked as alive, and if a previously alive path is dead, it will be marked as dead.
For some reason, if you see the default owner and the current owner of a particular LUN is not the same storage processor, then execute the following command, which will make the current owner of the LUN same as the default owner.
C:\Program Files\EMC\PowerPath> powermt restore dev=all
Instead of dev, you can also specify class in the powermt restore command. Class can be one of the following depending on your system.
symm – Symmetrix
clariion – CLARiiON
invista – Invista
ess – IBM ESS
hitachi – Hitachi Lightning TagmaStore
hpxp – HP StorageWorks XP, or EVA series
hphsx – HP StorageWorks EMA, or MA
all – All systems
