Using SDD to Move a VPATH From One VG to Another

Using SDD to Move a VPATH From One VG to Another

Post by Gabe Strass » Sat, 03 Aug 2002 04:04:53



Hello,

I am new to this group, and see some very useful information being
shared.  I am asking for some help in an area that is fairly new to
me.  I am a sysadmin for a large heterogeneous shop (mostly AIX and
Solaris).  I am familiar with the Logical Volume Manager but not with
the datapath devices.

A bit of background:  I am working with a Shark 2105, model E20.  We
have AIX 433 installed at ML10.

What I am trying to do for the first time is to move a vpath from one
volume group to another using an AIX server. I have found our web
interface (Storewatch) to be relatively unstable.  It will hang up
once in a while.  So, I decided "smitty" and the command line
interface is the best way to proceed.  I also have an innate
skepticism of GUI's.  (Will they REALLY do what you think?)

In reading the "SDD User's Guide" I have found a procedure for adding
a datapath device to an existing volume group. (Just follow the smitty
menu - System Storage Management; Logical Volume Manager; Volume
Groups; Add a Data Path Volume to a Volume Group.  Then fill in the
volume group and data path.)

I have found a "vpath" device that is apparently empty (no PP's
allocated). This vpath is in a different Volume Group.

So, can I do a "reducevg" on the vpath and volume group to "free up"
the vpath, and then use the smitty menu (Add a Data Path Volume to a
Volume Group) to in effect move the empty vpath to the new VG?  (Note,
the "new" VG  is not empty.)

If this is the way to go, are there any steps I omitted?

I am particularly hesitant to do this because we have hundreds of gigs
of critical production data on the Shark, and even though we do
backups, I don't relish the thought of restoring that much data.  Also
there is no "testbed" I can use to test out my method before doing it
on the production server.

Thanks for your time.

 - Gabe Strasser

 
 
 

Using SDD to Move a VPATH From One VG to Another

Post by Hans-Joachim Ehler » Sat, 03 Aug 2002 04:47:20




Quote:> Hello,

> I am new to this group, and see some very useful information being
> shared.  I am asking for some help in an area that is fairly new to
> me.  I am a sysadmin for a large heterogeneous shop (mostly AIX and
> Solaris).  I am familiar with the Logical Volume Manager but not with
> the datapath devices.

> A bit of background:  I am working with a Shark 2105, model E20.  We
> have AIX 433 installed at ML10.

> What I am trying to do for the first time is to move a vpath from one
> volume group to another using an AIX server.
<snip>
> In reading the "SDD User's Guide" I have found a procedure for adding
> a datapath device to an existing volume group. (Just follow the smitty
> menu - System Storage Management; Logical Volume Manager; Volume
> Groups; Add a Data Path Volume to a Volume Group.  Then fill in the
> volume group and data path.)

> I have found a "vpath" device that is apparently empty (no PP's
> allocated). This vpath is in a different Volume Group.

> So, can I do a "reducevg" on the vpath and volume group to "free up"
> the vpath, and then use the smitty menu (Add a Data Path Volume to a
> Volume Group) to in effect move the empty vpath to the new VG?  (Note,
> the "new" VG  is not empty.)

> If this is the way to go, are there any steps I omitted?

So you have
vg1 with a vpath1
vg2 with a vpath2

now you would like:
vg1
vg2 with vpath2 & vpath1

It should work but why not just delete the empty vpath and create a new one
?
Also check that you not hit any LVM limitation. ( max pp-size .e.a)

Quote:

> I am particularly hesitant to do this because we have hundreds of gigs
> of critical production data on the Shark, and even though we do
> backups, I don't relish the thought of restoring that much data.  Also
> there is no "testbed" I can use to test out my method before doing it
> on the production server.

No testbed ?. create a disk on the shark for your system and create a vpath
, assign it to a new vg  and test the step to a different new vg.

For more information about sdd, san, shark
Redbook:
SG24-6050 - A practical guide for san with pseries
SG24-6113 - Implemeting  fibre channel attachment on the ess
SG24-5420 - Ibm total storage server

Hajo

 
 
 

Using SDD to Move a VPATH From One VG to Another

Post by Gabe Strasse » Sat, 03 Aug 2002 06:49:33


Thank you for the reply.

(snip)

Quote:

>So you have
>vg1 with a vpath1
>vg2 with a vpath2

>now you would like:
>vg1
>vg2 with vpath2 & vpath1

>It should work but why not just delete the empty vpath and create a new one
>?

Okay, I think that was what I asked.  When I said  "moving" the empty vpath
from vg1 to vg2 really meant removing the empty path from vg1 and adding the
same vpath to vg2.

Maybe I am thinking of "vpath" as a physical disk, which it is not.  This is
because I still think in terms of hdisks. Still you think the steps will
work as I described?

Quote:>Also check that you not hit any LVM limitation. ( max pp-size .e.a)

Yes, I understand this.

(snip)

Quote:>No testbed ?. create a disk on the shark for your system and create a vpath
>, assign it to a new vg  and test the step to a different new vg.

I don't think we have any empty disks available.  I will look at the
information you sent me and download the redbooks. Those are very good
sources.

Thanks.

- Gabe

 
 
 

Using SDD to Move a VPATH From One VG to Another

Post by Hans-Joachim Ehler » Sat, 03 Aug 2002 14:48:34





> Thank you for the reply.

> (snip)

> >So you have
> >vg1 with a vpath1
> >vg2 with a vpath2

> >now you would like:
> >vg1
> >vg2 with vpath2 & vpath1

> >It should work but why not just delete the empty vpath and create a new
one
> >?

> Okay, I think that was what I asked.  When I said  "moving" the empty
vpath
> from vg1 to vg2 really meant removing the empty path from vg1 and adding
the
> same vpath to vg2.

> Maybe I am thinking of "vpath" as a physical disk, which it is not.  This
is
> because I still think in terms of hdisks. Still you think the steps will
> work as I described?

I think so but i can give you no garantie.

<snip>

Hajo

 
 
 

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