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.
# 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.
# 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.
# 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.
# 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.
# 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.
# 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.
# powermt display hba_mode
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 Q-IOs Mode
==============================================================================
1 qla2xxx optimal 2
0 0 Enabled
2 qla2xxx optimal 2
0 0 Enabled
7. powermt display path
– Display available I/O Paths.
This displays all available path for your SAN device.
# 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.
# 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?
# 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.
# 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.
# powermt set mode=standby hba=1
After the above command, you can see the mode for HBA#1
changed to standby, as shown below.
# 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.
# 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.
# powermt remove dev=sdd
# 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.
# 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.
# 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.
# 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
15. Powermt Save and
Load – Save and Restore PowerPath Configurations
powermt save – Save the current Powerpath
Configuration
If you are changing the PowerPath configurations for
testing purpose, you can save the current configuration using powermt save
command.
Use this method to backup the current PowerPath
Configurations.
# powermt save
This will save the current powermt configuration to
/etc/powermt.custom file. Following is the partial content of this file.
# cat /etc/powermt.custom
global:version:5.3.0.0.0:4.1.0
path_c:sdd:sdd:qla2xxx:0x111
path_c:sde:sde:qla2xxx:0x111
adapter: 1:
1:qla2xxx:0x111:1:0:111:0:11:0
adapter: 2:
2:qla2xxx:0x111:1:0:111:0:111:0
arrPort_c:04000000:04000000:111:111
mpext_cfg:unused:Mp:0:symm:0:0
...
...
If you want to store the current PowePath configuration to
a different file, do the following.
# powermt save file=/etc/powermt.21-Aug-2010
powermt load – Load a previously saved EMC PowerPath
Configuration
When you are testing EMC PowerPath configuration, if you
are not satisfied with the new configuration, you can go back to the previous
configuration.
For example, to restore the configuration to a specific
file that you created in the above powermt save example, do the following.
# powermt load file=/etc/powermt.21-Aug-2010
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