Vxvm dmp and EMC powerpath

 
Wivo
Occasional Advisor

Vxvm dmp and EMC powerpath

Hi,

 We are using VxVM  5.0.31.5 in our HPUX 11.31 systems.The servers connected to EMC CX4-480 C storage through SAN switches.

I am confused with the multipathing - if it is using vxvm dmp or EMC powerpath. How we can check which is enabled.

 

2 REPLIES 2
Cortes Albertino
Trusted Contributor

Re: Vxvm dmp and EMC powerpath

Hello,


Regarding DMP and from docs,

 

VxVM uses DMP metanodes (DMP nodes) to access disk devices connected to the
system. For each disk in a supported array,DMP maps one node to the set of paths
that are connected to the disk. Additionally, DMP associates the appropriate
multi-pathing policy for the disk array with the node. For disks in an unsupported
array, DMP maps a separate node to each path that is connected to a disk. The
raw and block devices for the nodes are created in the directories /dev/vx/rdmp
and /dev/vx/dmp respectively


A specified DMP node name must be a valid node in the
                /dev/vx/[r]dmp directory.

 

For example( on a system  running HP-UX B.11.23 and VxVM 5.0):

# date
Mon Oct 31 15:27:21 MET 2011

# vxdisk list
DEVICE       TYPE            DISK         GROUP        STATUS
c1t0d0       auto:hpdisk     rootdisk01   rootdg       online
c1t0d1       auto:LVM        -            -            LVM
c1t1d0       auto:none       -            -            online invalid
c1t1d1       auto:cdsdisk    c7t1d1       dgCFS        online shared
c1t1d2       auto:none       -            -            online invalid
c1t1d3       auto:none       -            -            online invalid
c1t1d4       auto:none       -            -            online invalid
c1t1d5       auto:LVM        -            -            LVM
c1t1d6       auto:LVM        -            -            LVM
c1t1d7       auto:none       -            -            online invalid
c1t2d0       auto:LVM        -            -            LVM
c1t2d1       auto:none       -            -            online invalid
c1t2d2       auto:cdsdisk    -            -            online
c1t2d3       auto:none       -            -            online invalid
c1t2d4       auto:none       -            -            online invalid
c1t2d5       auto:none       -            -            online invalid
c1t2d6       auto:cdsdisk    disk02       yidg         online
c1t2d7       auto:cdsdisk    disk01       yidg         online

 

# vxdisk list c1t1d1
Device:    c1t1d1
devicetag: c1t1d1
type:      auto
clusterid: cl_CFS
disk:      name=c7t1d1 id=1305275022.68.MYHOSTNAME
group:     name=dgCFS id=1305275705.70.MYHOSTNAME
info:      format=cdsdisk,privoffset=128
flags:     online ready private autoconfig shared autoimport imported
pubpaths:  block=/dev/vx/dmp/c1t1d1 char=/dev/vx/rdmp/c1t1d1
guid:      {4fcb182e-1dd2-11b2-8768-00306e271f6e}
udid:      HP%5F0450%5FF65E%5F0450F65E0629
site:      -
version:   3.1
iosize:    min=512 (bytes) max=1024 (blocks)
public:    slice=0 offset=32896 len=7141184 disk_offset=0
private:   slice=0 offset=128 len=32768 disk_offset=0
update:    time=1317114562 seqno=0.17
ssb:       actual_seqno=0.0
headers:   0 120
configs:   count=1 len=24072
logs:      count=1 len=3648
Defined regions:
 config   priv 000024-000119[000096]: copy=01 offset=000000 enabled
 config   priv 000128-024103[023976]: copy=01 offset=000096 enabled
 log      priv 024104-027751[003648]: copy=01 offset=000000 enabled
 lockrgn  priv 027752-027823[000072]: part=00 offset=000000
Multipathing information:
numpaths:   3
c1t1d1  state=enabled
c3t1d1  state=enabled
c7t1d1  state=disabled


The vxdmpadm utility is a command line administrative interface to DMP.


# vxdmpadm getsubpaths dmpnodename=c1t1d1
NAME         STATE[A]   PATH-TYPE[M] CTLR-NAME  ENCLR-TYPE   ENCLR-NAME    ATTRS
================================================================================
c1t1d1       ENABLED(A)   -          c1         XP1024       XP10240          -
c3t1d1       ENABLED(A)   -          c3         XP1024       XP10240          -
c7t1d1       DISABLED     -          c7         XP1024       XP10240          -


#  vxdmpadm getdmpnode nodename=c1t1d1
NAME                 STATE     ENCLR-TYPE   PATHS  ENBL  DSBL  ENCLR-NAME
=========================================================================
c1t1d1               ENABLED   XP1024       3      2     1     XP10240

 

# vxdmpadm getdmpnode nodename=c3t1d1
NAME                 STATE     ENCLR-TYPE   PATHS  ENBL  DSBL  ENCLR-NAME
=========================================================================
c1t1d1               ENABLED   XP1024       3      2     1     XP10240


# vxdmpadm getdmpnode nodename=c7t1d1
NAME                 STATE     ENCLR-TYPE   PATHS  ENBL  DSBL  ENCLR-NAME
=========================================================================
c1t1d1               ENABLED   XP1024       3      2     1     XP10240

 

 

And/or you may also have a look if foreign devices are defined in your system.

listforeign
                Lists information about foreign devices that have been
                defined to VxVM.

 

# vxddladm listforeign

The Paths included are
-----------------------

Based on Directory names:
-----------------------

Based on Full Path:
--------------------


Extracted from VxVM V5.X admin guide:

Foreign devices
The device discovery feature of VxVM can discover some devices that are controlled
by third-party drivers, such as for EMC PowerPath. For these devices it may be
preferable to use the multipathing capability that is provided by the third-party
drivers rather than using the Dynamic Multi-Pathing (DMP) feature. Provided
that a suitable array support library is available, DMP can co-exist with such
drivers. Other foreign devices, for which a compatible ASL does not exist, can be
made available to Veritas Volume Manager as simple disks by using the vxddladm
addforeign command. This also has the effect of bypassing DMP.


Hope it helps,

Cortes Albertino
Trusted Contributor

Re: Vxvm dmp and EMC powerpath