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Old 09-04-2012, 03:54 PM   #1
drakal30
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LVM , EMC Clariion SAN question


I am trying to map Clariion LUN #s to physical volumes inside Volume groups I can see out put like.

--- Physical volume ---
PV Name /dev/sdk1
VG Name vgDATA
PV Size 46.87 GB / not usable 32.00 MB
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 1499
Free PE 0
Allocated PE 1499
PV UUID qLtPDS-j9cl-0cIN-1AAR-eS3w-AikS-vcsBm5



I want to map that to this.

Pseudo name=emcpowerh
CLARiiON ID=APM00100601389 [RFWMS]
Logical device ID=600601608310270002699D866C4AE011 [LUN 22]
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 lpfc sdc SP B1 active alive 0 1
1 lpfc sdj SP A0 active alive 0 1
2 lpfc sdq SP B0 active alive 0 1
2 lpfc sdx SP A1 active alive 0 1


Thanks.
 
Old 09-05-2012, 10:50 AM   #2
MensaWater
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his requires that you install EMC Powerpath software onto the Linux system. EMC Powerpath is a licensed software (meaning you have to pay for it AND continue to pay for it in support to keep it licensed). EMC loves to audit its customers because they've given up trying to make their money by providing good products and support.
You might want to investigate using the native Linux multipath tool for the same purpose as Powerpath as it does not require any extra licensing from EMC and also works with other disk arrays such as Hitachi's. (Type "man multipath" for more details.)

If you have do have Powerpath installed and must use it you can use the "powermt" command to examine/configure setup for your presented disks. If you type "man powermt" you will see details of the command. A couple of commands:

powermt display
Outputs basic information and lets you know if all your paths are optimal

powermt display dev=all
Gives more detail similar to what you put in your post.

Note that your original disk is sdk and the example output you listed doesn't included sdk. I'm assuming these were just examples. You can't force a path that is not to the same physical disk (LUN) to be in the same multiple-path pseudo device but can add new paths if required. Basically both powermt and multipath can determine what is on the disks they see and add it to their configs automatically when you use the correct commands to rescan.
 
Old 09-05-2012, 12:20 PM   #3
drakal30
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Mensa, when you format the disks LVM renamed the powerpath devices to something like /dev/sdk the powermt command displays the powerpath names. I need to match the two.
 
Old 09-05-2012, 01:24 PM   #4
MensaWater
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LVM doesn't rename disks. It uses them as PVs (physical volumes) in the VGs (volume groups). You're sort of putting the cart before the horse.

You need to first present the disks (LUNS) to the OS. (e.g. /dev/sdc, /dev/sdj, /dev/sdq, /dev/sdx, /dev/sdk).

You then put the disks into your powerpath or multipath config. It is the emcpower[alpha] pseudo device for powerpath (or the dm [mpath] device for multipath) that is comprised of the original disks.

You then use the emcpower (or multipath) devices as your PV when you do the vgcreate. You should NOT use the underlying disks (/dev/sdk, /dev/sdc, /dev/sdo) as PV because those do not have multiple paths - they are single paths and it is powerpath (or multipath) that gives you the multiple path device. Any action you do to the multiple path device will work if any of the paths beneath it go away so long as one remains.

So in your original example your pseudo (multiple path) device is /dev/emcpowerh. This would be what you did the pvcreate on and what you would specify as a PV when you did the vgcreate. You should NOT use from that example ANY of the disks (sdc, sdj, sdq or sdx). If you use the pseduo device then if sdc, sdq and sdx all went away for some reason everything would continue to work because sdj is still there. If on the other hand you had specified sdq and it went away for some reason then things would break even though sdc, sdj and sdx are still OK because you didn't tell it to use the multiple path device but rather a single path.

Additionally Linux does sometimes rename paths to disks (e.g. sdc MIGHT become sdk on a future reboot) but the multipathing software would keep track of the underlying disks and so long as you'd specified the pseudo device
everything should continue to work.

Did you try running the powermt commands I gave in my prior post?

Did you review the powermt man page as I suggested?

Last edited by MensaWater; 09-05-2012 at 01:28 PM.
 
Old 09-06-2012, 08:49 AM   #5
drakal30
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Mensa I apologize I didn't explain my issue correctly.

I am refreshing a server and the SAN space has already been applied and LVMs setup. I need to map out the existing LVMs to existing LUNs on the CLARIION.
 
Old 09-06-2012, 01:36 PM   #6
MensaWater
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The "powermt display dev=all" shows you which Clariion LUN is associated with which emcpower[alpha] pseudo device and also shows you which /dev/sd* devices comprise the pseudo device.

What you wrote reminded me that once I wanted to change the actual pseudo device name because I wanted to hosts in a cluster to have the same name for the same Clariion LUNs. The command I used for that was:

"emcpadm renamepseudo -s emcpower[a-z] -t emcpower[a-z]" to reassign which pseudo device letter is used for a specific LUN.
e.g. You have LUN 102 showing up as emcpowerg but since it is 3rd LUN you want it to be emcpowerc instead:
emcpadm renamepseudo -s emcpowerg -t emcpowerc

If you have Navisagent installed and running on the Linux host you can also use navicli to see the LUN/pseudo device info:
/opt/Navisphere/bin/navicli lunmapinfo <IP OF CLARIION SPA or SPB>
 
  


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