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many path in legacy dsf .

 
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Rahul Tiwari
Advisor

many path in legacy dsf .

xyz:/#ioscan -m dsf
Persistent DSF Legacy DSF(s)
========================================
/dev/rtape/tape3_BESTn /dev/rmt/0mn
/dev/rmt/2mn
/dev/rtape/tape3_BESTb /dev/rmt/0mb
/dev/rmt/2mb
/dev/rtape/tape3_BESTnb /dev/rmt/0mnb
/dev/rmt/c19t0d0BESTnb
/dev/rdisk/disk14 /dev/rdsk/c4t0d1
/dev/rdsk/c6t0d1
/dev/rdsk/c8t0d1
/dev/rdsk/c10t0d1
/dev/rdsk/c12t0d1
/dev/rdsk/c14t0d1
/dev/rdsk/c16t0d1
/dev/rdsk/c18t0d1
/dev/pt/pt17 /dev/rscsi/c3t0d0
/dev/rscsi/c5t0d0
/dev/rscsi/c7t0d0
/dev/rscsi/c9t0d0
/dev/rscsi/c11t0d0
/dev/rscsi/c13t0d0
/dev/rscsi/c15t0d0
/dev/rscsi/c17t0d0
xyz:/#ioscan -fnNC disk
Class I H/W Path Driver S/W State H/W Type Description
===========================================================================
disk 4 0/0/2/1.0x0.0x10 UsbScsiAdaptor CLAIMED LUN_PATH USB SCSI Stack Adaptor
disk 3 64000/0xfa00/0x1 esdisk CLAIMED DEVICE HP LOGICAL VOLUME
/dev/disk/disk3 /dev/disk/disk3_p2 /dev/rdisk/disk3 /dev/rdisk/disk3_p2
/dev/disk/disk3_p1 /dev/disk/disk3_p3 /dev/rdisk/disk3_p1 /dev/rdisk/disk3_p3
disk 14 64000/0xfa00/0xf esdisk CLAIMED DEVICE HP HSV210
/dev/disk/disk14 /dev/rdisk/disk14
xyz:/#ioscan -funC fc
Class I H/W Path Driver S/W State H/W Type Description
===================================================================
fc 0 0/2/1/0/4/0 fcd CLAIMED INTERFACE HP AD193-60001 PCI/PCI-X Fibre Channel 1-port 4Gb FC/1-port 1000B-T Combo Adapter (FC Port 1)
/dev/fcd0
fc 1 0/5/1/0/4/0 fcd CLAIMED INTERFACE HP AD193-60001 PCI/PCI-X Fibre Channel 1-port 4Gb FC/1-port 1000B-T Combo Adapter (FC Port 1)
/dev/fcd1


Above is pasted the o/p of disk , fc and persistence and legacy addressing.
If i use persis. naming in a vgcreate i will not have to take care of extending
to alternate paths as in case of legacy ?why against one persis. i am getting many
legacy naming ...i see only 2 combo fc ?
5 REPLIES
sujit kumar singh
Honored Contributor
Solution

Re: many path in legacy dsf .

hi Rahul

yes if you are using the Persistent DSF of the form /dev/disk/diskXX you can be sure that you need not do not need to do a vgextend for alternate paths as the Alternate Pathing with the Dynamic Multipathing is a Default feature in the 11.31.

as you have 2 FC Interfaces, also consider the SAN swicthes and the Storage Controllers on the Storage being that give you the permutations and combinations of the path.

One Persistent DSF and many Legacy DSF the reason is that the PDSF is bound to the WWID of the LUN in the storage which is unique for a LUN in a Storage and many legacy DSF as the legacy DSF is boubd to the Legacy HW path.


Regards
Sujit

Regards
Sujit
Rahul Tiwari
Advisor

Re: many path in legacy dsf .

Dear Sujit ,
Thanks for reply .with 2 FCcard , 2 switches and 2 hsv210(EVA),could you please let me know how many paths i should be able to see in an ioscan o/p to a single LUN ?please let me know if you want some o/p.
if you conside this logic 2^2^2(two to the power of two to the power of 2), then also it should show me 16, not 8 links.
sujit kumar singh
Honored Contributor

Re: many path in legacy dsf .

Hi Rahul,


one more piece of information, in the New Mass Storage Stack that is the feature of 11iv3 whatever is the naming convention that you use be it Legacy or Persistent, or both the Native Multipathing is always there functional.

Also in the New MAss Generation Stack , Alternate pathing is not suggested not recommended as that is taken care by the native multipathing whatever naming convention you are using.

Yes i also had been seeing the same 8 paths for one LUN if there had been 2 SAN Swicthes, 2 FC Cards and 2 EVA controllers.

perhaps 2*2*2 is what that more closely defines that.


Regards
Sujit
VK2COT
Honored Contributor

Re: many path in legacy dsf .

Hello,

Sujit is right. Every path counts.

To check it in HP-UX 11.31:

# ioscan -m dsf /dev/disk/diskXX

# ioscan -m dsf /dev/dsk/cXtYdZ

So, to find out the agile DSFs for disks:

# ioscan -fnNC disk

The magic is flag "N".

Cheers,

VK2COT
VK2COT - Dusan Baljevic
Rahul Tiwari
Advisor

Re: many path in legacy dsf .

Thanks V2KCOT and Sujit,

Closing the thread.

Regards,