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bdeviprasad1
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March 25th, 2012 21:00
EMC power path On Linux
Hi,
we have provide only one lun(10GB) both the host servers(Linux 5.6, Kernel 2.6) than after we install EMC power path on the both the servers, When i check fdsik -l command it giving following output
[root@osdd1 scsi]# fdisk -l
Disk /dev/sda: 1195.9 GB, 1195997396992 bytes
255 heads, 63 sectors/track, 145405 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 145405 1167861240 8e Linux LVM
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 10240 10485744 5 Extended
Disk /dev/sdc: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 10240 10485744 5 Extended
Disk /dev/emcpowera: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System
/dev/emcpowera1 1 10240 10485744 5 Extended
Below is our Host to SAN Configuartion
We have server(IBM X3650M3) with Single HBA(Emulex) card having 2 ports, Two Switches(cisco MDS 9124) and EMC Clariion cx4-960 (in this we are using SP-A and SP-B deafult Ports ).
When we installed EMC Power Path why it showing multipathing? I need clarifcation on the same from ur side saying that is it ok to show the information like /dev/sdb and /dev/sdc. in my view it should show only one path i.e. /dev/emcpowera1 why it showing /dev/sdb and /dev/sdc paths
for more information on powerpath
[root@osdd2 ~]# powermt display dev=all
Pseudo name=emcpowera
CLARiiON ID=CKM00103100642 [OSDD]
Logical device ID=60060160FB0E26003E98DA345C67E111 [LUN 6]
state=alive; policy=BasicFailover; priority=0; queued-IOs=0;
Owner: default=SP B, current=SP B Array failover mode: 4
==============================================================================
--------------- Host --------------- - Stor - -- I/O Path -- -- Stats ---
### HW Path I/O Paths Interf. Mode State Q-IOs Errors
==============================================================================
7 lpfc sdb SP B0 unlic alive 0 0
8 lpfc sdc SP A0 active alive 0 0
Waiting for your response
this is correct, PowerPath will create emcpowerX device, you use this device when you create partitions, pvcreate ..etc. Native devices are always there, just like they are on AIX, HPUX. Each native device represents a path to the LUN, PowerPath knows that and takes advantages of that for loadbalancing, multipathing.
Hi Dynamox,
Issue is that
When we installed EMC Power Path why it showing multi LUN ?it should show only one LUN i.e. EMC powerpath LUN
for example:-Disk /dev/emcpowera: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System/dev/emcpowera1 1 10240 10485744 5 Extended
but the problem is that it showing multipathing which are as under,
[root@osdd1 scsi]# fdisk -l
Disk /dev/sda: 1195.9 GB, 1195997396992 bytes255 heads, 63 sectors/track, 145405 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 145405 1167861240 8e Linux LVM
Disk /dev/sdb: 10.7 GB, 10737418240 bytes64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System/dev/sdb1 1 10240 10485744 5 Extended
Disk /dev/sdc: 10.7 GB, 10737418240 bytes64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System/dev/sdc1 1 10240 10485744 5 Extended
Disk /dev/emcpowera: 10.7 GB, 10737418240 bytes64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Device Boot Start End Blocks Id System/dev/emcpowera1 1 10240 10485744 5 Extended
dynamox
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Posted March 25th, 2012 21:00
looks correct, it will display native paths. You are using unlicensed PowerPath so you are only protected from SP failover. Also you need to make sure each HBA is zoned to SPA and SPB.