How many unassigned LUNs / Harddisks

[Vipin Singhal]

Hi Everybody,
I need to make an inventory of all unassigned LUNs assigned to my server.
I think that there should be a considerable amount of disk that is already attached to the server but has not been assigned to any volume group.
How will I find the unassigned LUNs / HardDisks?
Thanks
Vipin

[Devender Khatana · Accepted solution]

Hi,

The samething was communicated earlier as well in your previous thread.

Make two lists of disk devices

1) Output from "strings /etc/lvmtab"

2) Output from "ioscan -fnC disk"

You will find that the entries in second output are actually more than in the first. The entries appearing in second output but not listed in first are unused disks. It is on assumption that the disks are configured using LVM.

The disks found like this will include all the paths to the unassigned disks. Divide the no. by no. of paths to the disk.

HTH,
Devender

[Vipin Singhal]

ok, I will compare both these command output file and I will come to know about unused harddisks.

I want to know that :
1.what does c??t??d?? means?
2.what is the standard to assign the HDD name?
3. LUN and Harddisk are the same thing?
4. How i will find Unused LUN / Harddisk size?

Please do let me know

[A. Clay Stephenson]

Danger Will Robinson!!! Just because a LUN or disk is unused with respect to LVM or VxVM, does not mean that it is unused. This would tell you nothing about raw devices that are used by applications (e.g databases) OR by devices that this host can see but might be in use by other hosts. The other obvious exceptions are whole disks (or LUN's) that are not under LVM but nevertheless have filesystems on them --- these are made even more difficult to spot when the filesystems are not mounted, at the moment.

There is really no bulletproof method of determining this except to really know your systems. It's easy to know the used devices; it's those devices that APPEAR to be unused that will get you everytime.

You essentially have to start with the array's or physical disks and account for each and every one of them.

[Vipin Singhal]

Hi,
You are right
But I had mount all the filesystem.
there is no unmounted filesystem.

Actually I need to create some more Volume groups, so this is must to know for me that I have any unused disk or not.

My BOSS told me that we have many disk that is alraedy attached to server but has not been assigned to any volume group.

Please let me know how i will findout unassigned LUN / Harddisk

[A. Clay Stephenson]

Oh, and don't overlook swap which does not have to be an LVM logical volume as well. swapinfo -t will tell you that.

[Vipin Singhal]

This is the output of swapinfo -t
# swapinfo -t
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4194304 826840 3367464 20% 0 - 1 /dev/vg00/lvol2
dev 20971520 833056 20138464 4% 0 - 1 /dev/vg00/swap2
reserve - 15554940 -15554940
memory 33520872 20920276 12600596 62%
total 58686696 38135112 20551584 65% - 0 -


1. how i will findout unassigned LUN / Harddisk?
2.what does c??t??d?? means?
3.what is the standard to assign the HDD name?
4. LUN and Harddisk are the same thing?

[A. Clay Stephenson]

Ioscan -C disk -fn will show you all the disk devices visible to your host. Because array LUN's may have multiple SCSI paths to the same physical LUN, you might have 1,2, or 3 paths to the same LUN. So what appears to be 3 devices might only be one device. Once again, you seem to want cookie-cutter answers for difficult problems. You have to start with the array management software and determine the LUN's and go from there.

Are you running VxVM in addition to LVM; if so, that will add an additional level to your task.

[A. Clay Stephenson]

1. how i will findout unassigned LUN / Harddisk?
A. I've already told that's very difficult (or at very difficult to be sure)?

2.what does c??t??d?? means?
c -- controller instance number
t -- SCSI target (or SCSI ID)
d -- Logical Unit Number

3.what is the standard to assign the HDD name? /dev/dsk/cXtYdZ (block) /dev/rdsk/cXtYdZ (character)

4. LUN and Harddisk are the same thing?
Sometimes yes; sometimes no.
-----------------------------------------
You really, really need to get some HP-UX training before you destroy data. At this point, it is not safe for you to be on the system. Questions 2 and 4 indicate that you lack even basic understanding and 2-4 must be answered before 1 can be tackled. None of this is intended to be insulting but rather to protect the system from great harm. The good news is that ignorance can be treated; stupidy, on the other hand, ... .

[Vipin Singhal]

Hey,
Can you please provide me the URL for this kind of training or documentation?

Thanks
Vipin

[A. Clay Stephenson]

Here's a good place to start:
http://education.hp.com/curr-unix.htm

Docs.hp.com also has a wealth of information but a training class or three is ideal because you will be able to do all sorts of damage on someone else's boxes and with non-critical data.

In addition to training and books the best suggestion I can give you is to talk your company into buying a Sandbox. You should be able to find a used HP server very cheaply and you can then learn to load and patch the OS, build filesystems, do LVM tasks, etc. in a completely safe environment. Anything I do that I am not completely confident of, I always first do it on my Sandboxes. Sandboxes are where you first deploy patches even before loading them into the Test environment.

[Devender Khatana]

Hi,

Here are plenty of docs to go through. But do not apply these immediately to your running boxes with critical data. Spare some machine for hands on practice of major administrative tasks and off course undergo some basic trainning.

HTH,
Devender

[Devender Khatana]

Hi,

Forget to mention the link. It is here

http://docs.hp.com/en/oshpux11iv2.html

HTH,
Devender