Creating a Volume Group

This post will describe how to:

1. Create a Volume Group
2. Create a Logical Volume within the VG containing a JFS2 filesystem that will be automatically mounted during boot.
3. Add a disk to the VG and mirror the data across 2 disks
4. Display LP>PP mappig and LVCB

1. Create a VG

 # mkvg -y vg0 -s64 -V99 hdisk3
vg0

-y VG name
-s PP size
-V VG Major Number

Now lets’ display which PV belongs to which VG and their status

# lspv
hdisk0          00c0e90dce6c290a                    rootvg          active
hdisk1          00cf405ea5c630a9                    rootvg          active
hdisk3          00cf405ea25a9e70                    vg0             active
hdisk4          00cf405ea25a9f84                    None
hdisk5          00cf405ea5ce7f72                    None
hdisk6          00cf405ea5ce8085                    None

2. Create a Logical Volume with a JFS2 Filesystem that will be automatically mounted on the /store mountpoint.

# crfs -v jfs2 -A yes -g vg0 -m /store -a size=1G
File system created successfully.
1048340 kilobytes total disk space.
New File System size is 2097152

-v Filesystem type
-A Automount at boot
-g VG in which the LV will reside
-m mount point

# mount /store
# df -g /store
Filesystem    GB blocks      Free %Used    Iused %Iused Mounted on
/dev/fslv07        1.00      1.00    1%        4     1% /store

3. Add a disk to the VG and mirror the data

# extendvg vg0 hdisk4

# mirrorvg -m vg0 hdisk4
0516-1804 chvg: The quorum change takes effect immediately.

-m Exact mapping of PP’s on both PV’s

# lslv fslv07 | grep LP
MAX LPs:            512                    PP SIZE:        64 megabyte(s)
LPs:                16                     PPs:            32
EACH LP COPY ON A SEPARATE PV ?: yes

The lslv command shows that we have 16 Logical Partitions stored on 32 Physical Partitions.

4. LP > PP mapping

# lsvg -M vg0

vg0
hdisk3:1-7
hdisk3:8        loglv01:1:1
hdisk3:9        fslv07:1:1
hdisk3:10       fslv07:2:1
hdisk3:11       fslv07:3:1
hdisk3:12       fslv07:4:1
hdisk3:13       fslv07:5:1
hdisk3:14       fslv07:6:1
hdisk3:15       fslv07:7:1
hdisk3:16       fslv07:8:1
hdisk3:17       fslv07:9:1
hdisk3:18       fslv07:10:1
hdisk3:19       fslv07:11:1
hdisk3:20       fslv07:12:1
hdisk3:21       fslv07:13:1
hdisk3:22       fslv07:14:1
hdisk3:23       fslv07:15:1
hdisk3:24       fslv07:16:1
hdisk3:25-31
hdisk4:1-7
hdisk4:8        loglv01:1:2
hdisk4:9        fslv07:1:2
hdisk4:10       fslv07:2:2
hdisk4:11       fslv07:3:2
hdisk4:12       fslv07:4:2
hdisk4:13       fslv07:5:2
hdisk4:14       fslv07:6:2
hdisk4:15       fslv07:7:2
hdisk4:16       fslv07:8:2
hdisk4:17       fslv07:9:2
hdisk4:18       fslv07:10:2
hdisk4:19       fslv07:11:2
hdisk4:20       fslv07:12:2
hdisk4:21       fslv07:13:2
hdisk4:22       fslv07:14:2
hdisk4:23       fslv07:15:2
hdisk4:24       fslv07:16:2
hdisk4:25-31

The lsvg command shows the mapping (-M) of the hdisk’s Physical Partitions to the Logical Partition’s of the Logical Volume fslv07 in the following format.

Disk Name.          LV Name
hdisk4:9            fslv07:1:2 -- Logical Partition copy Number 2
       |                   |
   Physical Partition 9    |
                           Logical Partition 1

So we can see from this line, that the second copy of the Logical Partition no. 1 of the Logical Volume fslv07 resides on the Physical Partition no. 9 of hdisk4.

Another possibility is to display the mapping on a LV level using the lslv command.

# lslv -m fslv07
fslv07:/store
LP    PP1  PV1               PP2  PV2               PP3  PV3
0001  0009 hdisk3            0009 hdisk4            
0002  0010 hdisk3            0010 hdisk4            
0003  0011 hdisk3            0011 hdisk4            
0004  0012 hdisk3            0012 hdisk4            
0005  0013 hdisk3            0013 hdisk4            
0006  0014 hdisk3            0014 hdisk4            
0007  0015 hdisk3            0015 hdisk4            
0008  0016 hdisk3            0016 hdisk4            
0009  0017 hdisk3            0017 hdisk4            
0010  0018 hdisk3            0018 hdisk4            
0011  0019 hdisk3            0019 hdisk4            
0012  0020 hdisk3            0020 hdisk4            
0013  0021 hdisk3            0021 hdisk4            
0014  0022 hdisk3            0022 hdisk4            
0015  0023 hdisk3            0023 hdisk4            
0016  0024 hdisk3            0024 hdisk4      

To display the Logical Volume Control Block of the specified LV type:

# getlvcb -AT fslv07
         AIX LVCB
         intrapolicy = m 
         copies = 2 
         interpolicy = m 
         lvid = 00cf405e00004c0000000135e3e508e9.2 
         lvname = fslv07 
         label = /store 
         machine id = xxxxxxxxx 
         number lps = 16 
         relocatable = y 
         strict = y 
         stripe width = 0 
         stripe size in exponent = 0 
         type = jfs2 
         upperbound = 32 
         fs = vfs=jfs2:log=/dev/loglv01:mount=true:account=false 
         time created  = Mon Mar  5 17:30:29 2012
         time modified = Mon Mar  5 17:42:04 2012
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5 comments
  1. Fred said:

    Many Thanks for your post it is very useful ; I did not know is possible to create directly FS with “crfs” command without creating first a logical volume.
    bye
    Fred.

    • Kaisar said:

      I agree with Fred. Thanks

  2. JJ said:

    You are welcome, thanks for Your feedback :), more tips, tricks and underlying concepts of LVM can be found in redbook: “AIX L.V.M. from A to Z” SG24-5432-00 (2010 update) on http://www.redbooks.ibm.com/

    Have a nice day
    JJ

  3. Gabriel G. said:

    Thanks a lot, very useful information.

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