Re: root drive size

A short introduction

1)
A volume group (VG) spans over 1 or more physical disk ( physical
volume - PV).
So a VG is a logical entity of physical disks and any later task is
normaly done within a VG

Now you need filesystems because thats what you are really working
with.

2)
On AIX you create first Logical Volumes ( LV) which will hold later the
Filesystem ( JFS) or give you even raw access to a disk.
Keeping No.1 in mind you will notice that you create these LV in a VG.
So a Logical Volume give you space for a filesystem and it is part of a
Volume Group.


The nice thing in AIX is: You can extend a Filesystem thus its
underlying LV on the fly until the VG which contains these LV has no
Space left. But if you have more unused disks you can even extend the
VG thus be able to extend the LV/FS

So getting back to your problem:
No, you can not extend the rootvg to use the rest of the harddrive(s)
because the rootvg own already both of them.
$ lspv
and you should see something like:
hdisk0 rootvg
hdisk1 rootvg

Yes, you can use the rest of the space for other logical
volumes/filesystems
Just do a
$ lsvg rootvg
look for free pps and you should see the the rootvg has about 280 GB
free of space for you. Its pretty much to waste for other stuff

Back to the comment from the AIX support:
Its bull*** ! Its a recommendation from the old days where you had the
small 2G drives and not much memory - if you have now enough money to
buy 2 more disk i would might think about it.

So if you are using the rootvg for your application you should create
filesystem for the applications data and use the mirroring option but
keep enought space free in case new have to increase system filesystems
! If you take no care the next call to IBM within the next 12 month is
just a question of time because then you would say: My /usr if full and
i can not extend it. :-)

Basic recommendation for new AIX systems:
1) Create for the user ROOT its own filessytem ( /root ) and change the
home directory to ( /root) . Otherwise you are going to trash your
system on the long run if you not keep an eye on / ( Which is the home
directory for the user root - Do not forget to move the .ssh and
..rhosts to the new home diretcory as well )

2)
Extending paging page and filesystem on the fly is pretty easy. Since
AIX 5.3 you can even shrink the FS
For extending paging space see:
$ man chps
For extending filesystem see
$ man chfs
or use
$ smitty
the man in black


Some usefull comments to the VG and LV and PV
$ lsvg
$ lsvg -l
$ lslv
$ lspv

and get at least a basic AIX training.
hth
Hajo

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