LVM quick reference

News	See also	Redbooks	IBM Links	Recommended Links	Recommended eBooks and Papers	Reference
what disks are in the root volume group	How many disks are on the system	Create a volume group	Add a disk to the root volume group	Make sure the disks are in an active state	Mirror the logical volumes	Create the boot image on the new disk
Extend the size of filesystem	Remove a file system

Sadly, the original web site that this useful intel was on is no longer available.

IBM AIX: Volume Management
IBM AIX Logical Volume Management
System Administrator Information

How to create a file system

Log into server and gain root access
Select a Volume Group to create the file system under: lsvg (shows what volume groups are on the server)
Check to see how much disk space is currently available on the desired volume group: lsvg VGNAME (Check for Free PPs:) If there is enough disk space proceed to the next step
From the results of the lsvg VGNAME Check for the PP size in Megabytes. This will be 16, 32, 64 or 128 MB. The PP size is VERY important to remember as this will determine the number of Physical Partitions that will be used. If the wrong number is used this will either give too much or not enough disk space to the file system but will not cause any failures. You can NOT shrink a file system after its created so this is the only chance to get it correct without deleting and starting over.
Open a calculator: Enter the number of Megabytes (MB) that you wish to have as the file system size in the calculator, divide that by the number of the PP Size (2048 “Size of file system” / 32 “PP Size” would equal 64 PP’s to be used in the file system creation)
Create the Logical Volume: Run the following command ‘smitty fs’
Select ‘Add a logical Volume’
Select ‘Volume Group Name’:
- Enter the ‘Logical Volume NAME’: There is 15 character limit for this field.
- Enter the number of Physical Partitions: Number of PPs from the above mathematical process
- Select Logical volume TYPE: enter JFS or JFS2 based on requirements. Unless the customer requests JFS select JFS2.
- Select Range of Physical Volumes:
- Change from minimum to maximum
- Press Enter to accept changes. System will run and return an “OK” in the upper left hand corner when the command is complete.
- Exit Smitty lv and enter ‘smitty fs’
Select Add / Change / Show / Delete File Systems
Select either Journaled File Systems or Enhanced Journaled File Systems
Select Add an Enhanced Journaled File System on a Previously Defined Logical Volume
Select the Logical Volume Name that you created in the previous step
Enter the mount point:
- Select yes for Mount AUTOMATICALLY at system restart
- Press enter to create the file system
- Exit smitty fs and run the following command: ‘mount /PATH
- Confirm that the file system has been created (df –k |grep PATH)
- Set the permissions and ownerships per customer request
- Task is now complete

How to expand a file system

Log into server and gain root access
Run the command: ‘smitty fs’
Select Add / Change / Show / Delete File Systems
Select either Journaled File Systems or Enhanced Journaled File Systems
Select Change / Show Characteristics of an Enhanced Journaled File System and select the file system that you wish to expand
Convert the number of Megabytes / Gigabytes requested by the customer into 512K blocks:
Bring up http://www.mydasd.com/converison.htm in a web browser.
In the Convert what quantity? Field enter the amount of space requested by the customer. Make sure to click the proper options in the left box below the quantity field. The box on the right should always be set to Bytes. Always click the Convert button to make sure you have an updated number in the display box.
Open a calculator: Enter the number from the webpage and divide that number by 512 (10 GB = 10,737,418,240: 10737418240 / 512 = 20971520)
In the smitty fs window take the number that is currently listed in the SIZE of file system (in 512-byte blocks) field and add that to the number from the above line in your calculator (Current size + SUM from above line = new size)
Enter the finial number in your calculator into the SIZE of file system field
Press Enter to accept changes. System will run and return an “OK” in the upper left hand corner when the command is complete.
Task is now complete

How to create a volume group (Using Powerpath)

To bring LUNs in as disks type cfgmgr
Type lspv |grep hdiskpower (Look for disks that are not assigned, they will be listed as “None”
Type ‘smitty’ and press enter
Select ‘System Storage Management (Physical & Logical Storage)’
Select “Logical Volume Manager”
Select “Volume Groups”
Select “Add a Volume Group with PowerPath Devices”
Enter the Volume Group Name to be created
Select “Physical partition SIZE in megabytes” (choose 32 MB by default unless directed otherwise)
Select “PHYSICAL VOLUME names”
Select the disks to be added to the new Volume Group. Press enter
Make sure that the line that says Activate volume group AUTOMATICALLY is marked “Yes”
Press Enter start changes, you will be prompted “are you sure”.
If you are sure press enter. Make sure you have selected the right information as you can NOT back out the changes.
From the command line prompt: type ‘lspv |grep hdiskpower’ you should now see that the disks that were assigned as “None” are now assigned to your new Volume Group.
Exit smitty
Task is now complete

How to re-create a file system when there are sub file systems present

Create _new file system
Un-mount all /PATH/srvr####/ sub file systems
Copy data to fromthe /PATH/srvr#### file system to the _new one
Un-mount /PATH/srvr####
Re-name /PATH/srvr#### to /clocal/srvr####_old
Re-Mount _old file system
Change the mount order in /etc/filesystems so that /PATH/srvr####_new mounts before all of the sub file systems
Un-mount _new file system
Change mount point of _new and drop the _new part
Mount /PATH/srvr#### file system
Create sub file systems (cntr0001 dblog01) mount points (directories)
Run a mount on the rest of the file systems

Task	AIX 5L Version 5
Storage structure	A disk is composed of physical partitions. A physical volume is a physical disk the same thing as a disk. A volume group is composed of physical volumes. A volume group is divided into logical volumes. A filesystem is placed into a logical volume. A logical volume is extensible and can reside on more than one volume.
Run multiple tasks in a GUI environment	`smit lvm` `wsm`
Move a logical volume to another logical volume	`migratepv`
Create a logical volume	`mklv`
Extend a logical volume	`extendlv`
Remove a logical volume	`rmlv`
Create a volume group	`mkvg`
Remove a disk from a volume group	`reducevg`
Add disks to a volume group	`extendvg`
Change logical volume settings	`chlv`
Display volume group information	`lsvg`
Display performance statistics for storage	`lvmstat`
Manage volumes	`chlv` `mklv` `rmlv`
Add a copy to an existing volume	`mklvcopy`

IBM Disk Utilities in a nutshell

IBM Volume Manager in a nutshell

Listing Volume Groups

lsvg

rootvg

HACMPvg

paritemvg

yatirimvg

pbackupvg

ybackupvg

Detailed information about a Volume Group

root@paritem:/ >lsvg paritemvg

VOLUME GROUP:paritemvgVG IDENTIFIER:00c076eb00004c000000010852f95257

VG STATE:activePP SIZE:32 megabyte(s)

VG PERMISSION:read/writeTOTAL PPs:3196 (102272 megabytes)

MAX LVs:256FREE PPs:5 (160 megabytes)

LVs:2USED PPs:3191 (102112 megabytes)

OPEN LVs:2QUORUM:3

TOTAL PVs:4VG DESCRIPTORS: 4

STALE PVs:0STALE PPs:0

ACTIVE PVs:4AUTO ON:no

MAX PPs per VG:32512

MAX PPs per PV:1016MAX PVs:32

LTG size (Dynamic): 1024 kilobyte(s)AUTO SYNC:no

HOT SPARE:noBB POLICY:relocatable

Listing logical volumes in a Volume Group

root@paritem:/ >lsvg -l paritemvg

paritemvg:

LV NAMETYPELPsPPsPVsLV STATEMOUNT POINT

parfslogjfs2log111open/syncdN/A

paritemlvjfs2319031904open/syncd/paritem

Detailed information about a Logival Volume

root@paritem:/ >lslv paritemlv

LOGICAL VOLUME:paritemlvVOLUME GROUP:paritemvg

LV IDENTIFIER:00c076eb00004c000000010852f95257.2 PERMISSION:read/write

VG STATE:active/completeLV STATE:opened/syncd

TYPE:jfs2WRITE VERIFY:off

MAX LPs:4096PP SIZE:32 megabyte(s)

COPIES:1SCHED POLICY:parallel

LPs:3190PPs:3190

STALE PPs:0BB POLICY:relocatable

INTER-POLICY:maximumRELOCATABLE:yes

INTRA-POLICY:middleUPPER BOUND:32

MOUNT POINT:/paritemLABEL:/paritem

MIRROR WRITE CONSISTENCY: on/ACTIVE

EACH LP COPY ON A SEPARATE PV ?: yes

Serialize IO ?:NO

Listing physical volumes in a Logical Volume

root@paritem:/ >lslv -l paritemlv

paritemlv:/paritem

PVCOPIESIN BANDDISTRIBUTION

hdisk5798:000:00020%160:160:159:160:159

hdisk6798:000:00020%160:160:159:160:159

hdisk7797:000:00020%160:160:159:160:158

hdisk4797:000:00019%160:159:159:160:159

Listing All Physical Volumes in the system

root@paritem:/ >lspv

hdisk000c076eb47dc9ccdrootvgactive

hdisk100c076eb48a321d1rootvgactive

hdisk200c076eb52dc8486HACMPvg

hdisk300c076eb52dc87cbHACMPvg

hdisk400c076eb52f945b8paritemvgactive

hdisk500c076eb52f948ecparitemvgactive

hdisk600c076eb52f94c26paritemvgactive

hdisk700c076eb52f94f61paritemvgactive

hdisk800c076eb52f9882eyatirimvg

hdisk900c076eb52f98b5cyatirimvg

hdisk1000c076eb52f98e8byatirimvg

hdisk1100c076eb52f99260yatirimvg

hdisk1200c076ebb148f11dpbackupvgactive

hdisk1300c076ebb148f470pbackupvgactive

hdisk1400c076ebb14935e2ybackupvg

hdisk1500c076ebb1493921ybackupvg

Detailed information about a Physical Volume

root@paritem:/ >lspv hdisk5

PHYSICAL VOLUME:hdisk5VOLUME GROUP:paritemvg

PV IDENTIFIER:00c076eb52f948ec VG IDENTIFIER00c076eb00004c000000010852f95257

PV STATE:active

STALE PARTITIONS:0ALLOCATABLE:yes

PP SIZE:32 megabyte(s)LOGICAL VOLUMES:1

TOTAL PPs:799 (25568 megabytes)VG DESCRIPTORS:1

FREE PPs:1 (32 megabytes)HOT SPARE:no

USED PPs:798 (25536 megabytes)MAX REQUEST:1 megabyte

FREE DISTRIBUTION:00..00..00..00..01

USED DISTRIBUTION:160..160..159..160..159

Listing logical volumes on a Pyhsical Volume

root@paritem:/ >lspv -l hdisk5

hdisk5:

LV NAMELPsPPsDISTRIBUTIONMOUNT POINT

paritemlv798798160..160..159..160..159 /paritem

Changing FileSystem Properties

# first check the avaliable free space

# previously explained

lsvg <volume group name>

# adding 40GB to a mount point

Chfs –a size=+20000000 /pbackup(20000000/512=39063MB)

# can also be made by smitty chfs

Smitty chfs > Change / Show Characteristics of an Enhanced Journaled File System > Select the file system

# changing a mount point

Chfs –d /pbackup /paritem_backup

# config file

/etc/filesystems

# further chfs options are in chfs manual pages

man chfs

# if there is hacmp managed system then

# changing filesystem should be made by “smitty hacmp”

Smitty hacmp > System Management > Logical Volume Management > Shared File Systems > Enhanced Journaled File Systems > Change / Show Characteristics of a Shared Enhanced Journaled File System > Select the File System

LVM quick reference

How to expand a file system

How to create a volume group (Using Powerpath)

How to re-create a file system when there are sub file systems present

Recommended Links