Ralph Shumaker wrote:
>..
> I made my first attempt to follow this outline from the fc7 install dvd,
> then from the knoppixV5.1.1 dvd, then finally from the fc4 install dvd.
> 
>>
>> At the shell prompt # lvm      # this gets you an lvm prompt
> 
> This did nothing in the fc7 install dvd except give me a new command
> prompt (dead end for that path)...

Did nothing?? Not even "..command not found"?
Weird!

>.. Through knoppix and fc4, this gave me
> the lvm> prompt.
> 
>> lvm> vgscan                         # scan volume groups to see what's
>> there
>> lvm> vgdisplay /dev/VolGroup00/Slash          # look in detail at the
>> logical volume
> 
> This gives:
>  Invalid volume group name: VolGroup00/Slash

Yes there was a typo in the instructions. It may help to see little
classification of the perplexing lvm command repertoire.

The lvm system involves 3 classes of storage "things"

 PV: _Physical Volumes_ are the real disk storage resources consigned to
management by the logical volume manager

 VG: _Volume Vroups_ are the pools of storage built from PVs and from
which  pieces of storage (LVs) are dealt out

 LV: _Logical Volumes_ are the end-product that the logical volume
manager delivers to the system for building a filesystem on.

Given that, then commands with a vg prefix, like
 vgXXX
tell/do something about/with volume groups

(and similarly for pvXXX and lvXXX)

I would also point out that the vgdisplay and lvdisplay commands may
spit out more information than one wants, sometimes. But there is a more
compact format that you may wish to use for the benefit of discovering
names or sizes.

Try
  pvs
  vgs
  lvs

A further general observation that may help understand the names, is
that volume group names are simply subdirectories of /dev.

Thus
  ls -l /dev/VolGroup00
might give (for example)
  ... Slash -> /dev/mapper/VolGroup00-Slash
  ... Home  -> /dev/mapper/VolGroup00-Home
  ...

The logical volume names are in turn the entries in the volume group
directory. It's a confusing detail that LV names are symlinks to devices
located under the /dev/mapper directory. Can't do anything about that, I
suppose. The /dev/mapper/XXX thingies are the "devices" used by the system.

</classification-mumbling>


Now, there was probably something else overlooked in Carl's instructions.

When I boot Knoppix in order to poke around with my hard drive, I have
to run not only
  vgscan
but
  vgchange -ay
to "activate" the VG, before lvm will create its subdirectories in /dev.

Thus lvm knows which and where.., but the dev-dir-links-stuff doesn't
exist until VGs are activated.

Then you can do the e2fsck, etc

>..<snip>

Hope this helps.

Regards,
..jim


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