TITLE    : Howto replace a hard drive that contains a single volume group.
OS LEVEL : AIX 
DATE     : 19/05/99
VERSION  : 1.0

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In the following example, an RS6000 has 2 disks, the first contains rootvg 
and the AIX operating system files, and the second contains datavg and 
application files. The second disk is reporting errors in the errorlog and
even though it is still running it will be replaced.

lspv

hdisk0         002104067be1ef0f    rootvg
hdisk1         00210406da6217f8    datavg     


1, Find out details of the volume group:-

   lsvg datavg

   VOLUME GROUP:   datavg          VG IDENTIFIER:  00210406d76313c6
   VG STATE:       active          PP SIZE:        4 megabyte(s)
   VG PERMISSION:  read/write      TOTAL PPs:      572 (2288 megabytes)
   MAX LVs:        256             FREE PPs:       571 (2284 megabytes)
   LVs:            1               USED PPs:       1 (4 megabytes)
   OPEN LVs:       0               QUORUM:         2
   TOTAL PVs:      1               VG DESCRIPTORS: 2
   STALE PVs:      0               STALE PPs       0
   ACTIVE PVs:     1               AUTO ON:        yes   

   The output of this command will be needed to re-create the volume
   group later on.


2, Find out how many file systems are on the volume group :-

   lsvg -l datavg

   datavg:
   LV NAME       TYPE       LPs   PPs   PVs  LV STATE      MOUNT POINT
   datalv        jfs        500   500   1    open/syncd    /data
   loglv00       jfslog     1     1     1    open/syncd    N/A
   
   The output of this command will be needed to re-create the filesystems
   later on.

   Ensure that each filesystem is backed up using either tar, cpio or
   backup.


3, For each mount point listed in the "lsvg -l datavg" command, umount and 
   remove the filesystem:-
                                                           
   umount /data
   rmfs /data


4, Turn off the volume :-
 
   varyoffvg datavg


5, Remove the volume group from the system :-

   export datavg


6, Find out the scsi id of the disk that is being replaced :-

   lsdev -Cs scsi

   hdisk0 Available 04-A0-00-0,0  Other SCSI Disk Drive
   cd0    Available 04-A0-00-4,0  SCSI Multimedia CD-ROM Drive
   hdisk1 Available 04-A0-00-5,0  Other SCSI Disk Drive                           


7, Remove the disk drive from the system :-

   rmdev -l hdisk1 -d


8, Shutdown the system and replace the disk, ensure that the new disk
   is set for the same scsi id as the old disk. Reboot the system after
   replacing the disk, you may want to boot in "SERVICE" mode to check
   that the new disk is on the correct scsi id and can be seen by the
   system by running "CERTIFY" on the disk.


9, Check that the new disk can be seen by the system and is available:-

   lsdev -Cs scsi

   hdisk0 Available 04-A0-00-0,0  Other SCSI Disk Drive
   cd0    Available 04-A0-00-4,0  SCSI Multimedia CD-ROM Drive
   hdisk1 Available 04-A0-00-5,0  Other SCSI Disk Drive                           

   lspv

   hdisk0         002104067be1ef0f    rootvg
   hdisk1         none                None       


   If the new disk does not report a "Physical volume identifier", then
   you need to make the hard drive a physical volume :-

   chdev -l hdisk1 -a pv=yes

   lspv

   hdisk0         002104067be1ef0f    rootvg
   hdisk1         00210406dbbccbe1    None 


10, Re-create the volume group on the new disk :-

    mkvg -y datavg -s 4 hdisk1   

    Where 4 is the "PP SIZE" of the volume group.
    (vg size of                         upto  4.064 Gig =  4 Meg PP size
     vg size of greater than  4.064 and upto  8.128 Gig =  8 Meg PP size
     vg size of greater than  8.128 and upto 16.256 Gig = 16 Meg PP size 
     vg size of greater than 16.256 and upto 32.512 Gig = 32 Meg PP size
     etc).

11, For each mount point listing in the "lsgv -l datavg" command, recreate 
    the logical volume, filesystem and mount the filesystem :-

    mklv -y datalv datavg 500  
    crfs -v jfs -d datalv -m /data -A yes
    mount /data                                   

    Where  /data is the "MOUNT POINT"
          datalv is the "LV NAME"
             500 is the "LPs"

12, Restore the data to each filesystem.