Identifying number of hardware devices involved from multipath

[satish]

Hi erman,

From below output, can you say how many hwa ports,controller,switch ports etc are involved?

PRD-ARCH01 (360002ac0000000000000006b0001c9fc) dm-19 3PARdata,VV
size=100G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
`-+- policy='round-robin 0' prio=50 status=active
  |- 2:0:0:24 sdo  8:224   active ready running
  |- 1:0:1:24 sdec 128:64  active ready running
  |- 2:0:1:24 sdbv 68:144  active ready running
  `- 1:0:0:24 sdgj 131:240 active ready running

Thank you

[ErmanArslansOracleBlog]

Yes. Sort of..
There is unique identifier of the device there -> 360002ac0000000000000006b0001c9fc
So you can use that id on the storage side and understand..
It seems storage is a 3PAR

Those scsi ids are telling you the following info ->

The first one , the host bus adapter (HBA) number

Second; The value for channel is the SCSI bus address.

Third, the value for Id is the target ID.

Last one , the value for Lun is the SCSI LUN.

For instance;  2:0:0:24  -> HBA 2, Channel 0, target ID 0 and Lun 24..

So, as you see in the output that you have sent; one Disk ( a storage disk probably) is seen from 4 paths.. 2 of them are based from HBA 1, and 2 of them are based on HBA 2.. They also differ in the target ids.. Linux sees the disk as 4 different disks.. This is normal and expected.. You will however; use the actual device name according to your multipath conf.. (not! the ones named with the scsi disk prefix sdc, sdec etc..)

[satish]

Thanks for the update.

So,these sdo,sdec,sdbv,sdgj are just paths and not physical devices,please correct me?

 |- 2:0:0:24 sdo  8:224   active ready running
  |- 1:0:1:24 sdec 128:64  active ready running
  |- 2:0:1:24 sdbv 68:144  active ready running
  `- 1:0:0:24 sdgj 131:240 active ready running

Thanks,
Satish

[ErmanArslansOracleBlog]

These are special files for accessing the underlying disk devices.. /dev/sd* these are for scsi devices.. We say everything is based on files in Linux, right.. So ..  But they will be in the backend.. You will use the multipath devices names instead. The multipath devices will handle the access to those scsi devices..