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AIX LVM Tasks

what disks are in the root volume group
 

# lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            546         186         00..00..00..77..109

Now let's see how many disks are on the system
 

# lspv
hdisk0          00cf4f5d02a3c139                    rootvg          active
hdisk1          00cf4f5da1ca9590                    none 
#

1. lsdev -C -c disk  -> lists available disks (and the hdisk#) on the server
2. mkvg -y "<VG_NAME>" hdisk#  --> creates the volume group on the named hard disk
3. varyonvg <VG_NAME>  --> activates the volume group

Add a disk to the root volume group (extend the volume group) extendvg <vg> <disk#>

# extendvg -f rootvg hdisk1

• Verify the disk has been successfully added to the vg

  lsvg -p <vg>

Make sure the disks are in an active state
 

# lspv
hdisk0          00cf4f5d02a3c139                    rootvg          active
hdisk1          00cf4f5da1ca9590                    rootvg          active

 Mirror athe logical volumes that exist on a given volume group

# /usr/sbin/mirrorvg rootvg hdisk0 hdisk1

0516-1124 mirrorvg: Quorum requirement turned off, reboot system for this
to take effect for rootvg.
0516-1126 mirrorvg: rootvg successfully mirrored, user should perform
bosboot of system to initialize boot records. Then, user must modify
bootlist to include: hdisk0 hdisk1.

• lsvg -l

•  mklvcopy -s y <LV_NAME> 2

Create the boot image on the new disk and put it on the bootlist
 

# bosboot -ad /dev/hdisk1

bosboot: Boot image is 25166 512 byte blocks.
bootlist -m normal hdisk0 hdisk1

# lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk1            active            546         186         00..00..00..77..109
hdisk0            active            546        186         00..00..00..77..109

Filesystem Procedures

• See below the procedure for creating a logical volume and a filesystem using JFS:

1. "df" to see the filesystem, it's current size, % utilization and the name of it's logical volume
2. "lslv <logical_volume>" to show information about the logical volume including it's volume group name.
3. "lsvg <volume_group>" to show information about the volume group, including number of free pp's and the pp size
4. If there are not enough free pp's then see below for procedure to add a disk to a volume group.
    
5. "chfs -a size= +4194304 <MOUNT_POINT>" to grow the filesystem by 2 GB (4194304=2*1024*1024*1024/512)
   • NOTE:  Growing the file system will automatically grow the logical volume
6. df" shows the file system's current size is 2 GB more than before.

• Error Message:  0516-787 extendlv: Maximum allocation for logical volume <LV_Name> is 512.
  • Maximum number of LPs for the logical volume has been exceeded - must increase the allocation
  • Calculate the number of LPs needed = LV Size in MB / LP size in MB
  • chlv -x <new_max_lps> <logical_volume>

1. Unmount the filesystem
2. Remove the logical volume "rmlv <lv_name>"
3. Remove the filesystem information from /etc/filesystems

1. Create the file system
   1. crfs -v jfs -m /usr/sharenew -g rootvg -a size=8192
   2. this makes a logical volume in the root volume group of 4MB that uses jfs
2. Mount the volume
   1. mount /usr/sharenew
3. Move the files from the old file system (/usr/shareold)
   1. cd /usr/shareold
   2. tar cf - | (cd /usr/sharenew; tar xvf -)
   3. cd
4. Unmount the file systems
   1. umount /usr/sharenew
   2. umount /usr/shareold
5. Remove the old file system and it's logical volume
   1. rmfs /usr/shareold
6.   
   1. chfs -m /usr/shareold /usr/sharenew
7. Mount the new filesystem
   1. mount /usr/shareold
8. Delete the temporary mount point
   1. rmdir /usr/share

Logical Volume Procedures
 

1. lsvg to determine the size of the PP
2. lslv in similar logical volumes to determine if mirroring is in effect
    
3. Calculate the number of PPs needed for the logical volume
    
   1. bc
   2. scale=2
   3. <size of lv in MB>/<size of PP in MB>
   4. quit
       
4. mklv -y  "<LV_NAME>" <VG_NAME> <# of LPS>  --> creates the logical volume
5. crfs -v jfs -d <LV_NAME> -m /<MOUNTPOINT> -A yes   --> makes the filesystem, creates the mountpoint and puts it in /etc/filesystems
6. mount /<MOUNTPOINT>  --> mounts the new fileystem
7. df /<MOUNTPOINT>  --> verifies the mount and the size of the new filesystem
8. Check the ownership and permissions of the new mount point
   • ls -ld <mountpoint>
   • chown owner:group <mountpoint>
   • chmod XXX <mountpoint>
      
9. If mirroring is in effect, then mirror this logical volume to another disk (original and 1 mirror):
   • mklvcopy -s y <LV_NAME> 2
      

Volume Group Procedures

1. lspv  --> determine the hdisk#
    
2. extendvg rootvg hdisk<number>  --> add the hdisk to the volume group
    
3. lspv  -->  verify that the hdisk has been successfully added to the volume group
    
4. chvg -Q 'n' rootvg  -->  change the quorum so that the vg will stay active if one of the mirrors fail
    
5. mirrorvg -S -c 2 rootvg  --> mirror all of the logical volumes in the volume group
    
6. lsvg -l rootvg  --> verify successful mirroring (pps will appear "stale" until synchronization is complete).
    
7. bosboot -a  -->  update the boot image information
    
8. bootlist -m normal -o hdisk0 hdisk1  --> create a new bootlist
    
9. bootlist -m normal -o  --> verify the bootlist is correct
    

1. "lsvg <volume_group>" to show the total PP's available in the volume group =1250
2. "lsvg -l <volume_group>" to show the total PP's used in all logical volumes in that volume group (showed sys1log, the jfs log was using 2 PP's)
3. "chlv -x 1248 <logical_volume>" to change the maximum number of LP's from 1100 to 1248 (1250 PP's in the volume group - 2 PP's used by the jfs log  = 1248 available)

Physical Disk Procedures
 

• lsvpcfg
  • This will show disks/vpaths and the volume group they are allocated to
• lspv|grep None
  • This will show pvs and whether they are asssociated with a volume group
  • Note:  For vpaths, the hdisks will show as none, but they may be allocated to a vpath - you must grep each hdisk with the lsvpcfg

• Allocate the new lun on the SAN
• Run "cfgmgr"
• Verify the new vpatch/hdisk by running "lsvpcfg"
  • There should be a new vpath and it should be available with no volume group - if not, rerun cfgmgr
     

• lsvg -p <volume group>

Logical Volume Manager

During the early stages of UNIX®, the management of physical disks was always a daunting task because of the restrictions on allocating the actual physical space. You'd have to define physical partitions, and each physical partition would actually be of a fixed size. Additionally, a physical disk could only have eight physical partitions, so the customer had to select the correct size of each partition before installing the system.

A major restriction of the physical partition was that each partition had to be contiguous; meaning you could not span multiple drives. What evolved from this messy picture was a new, flexible technique to manage the allocation, known as logical volumes. Here are some of the benefits:

• Logical volumes solve non-contiguous space problems.
• Logical volumes can span multiple disks.
• The size of logical volumes can dynamically increase.
• You can relocate and mirror them.

AIX and Solaris offer different methods for using logical volumes. With Solaris, it does not come ready out of the box. You need to determine which LVM to use, and decide whether or not to use SVM or VERITAS. While VERITAS offers the VERITAS Foundation suite for AIX 5L™, it is typically not used in AIX environments, as it is not necessary. VERITAS Volume Manager (VxVM) is a storage management subsystem that enables you to manage physical disks as logical devices called volumes. It is important to reiterate that this product is third-party software, and you will pay handsomely for it.

The LVM has been a feature of the AIX operating system since Version 3, and it is installed automatically with the operating system. Table 1 helps lay out some of the differences between AIX and VERITAS, and it also compares the commands (for the complete table, see Resources). While the version numbers might be different, the concepts and commands remain the same.

Figure 1 illustrates how the physical disk relates to the actual logical partitions.

Recommended Links

Transition from Solaris to AIX

AIX File Structure Volume Logical Tips

• AIX Reference for Sun Solaris Administrators: This IBM Redbook is for Solaris administrators who want to transfer their knowledge of Solaris UNIX skills to the AIX 5L.
  
   
• Quick Reference: AIX Journaled File Systems and Veritas File System: This IBM white paper compares the Veritas Filesystem to JFS.
  
   
• Solaris to AIX Migration: A Guide for System Administrators: A great resource to reference when migrating from Solaris to AIX.
   
• AIX Logical Volume Manager and Veritas Volume Manager: For a document to help system administrators co-manage AIX systems from the LVM point of view, read the IBM white paper .
   
• Introducing SMIT: The powerful AIX System Management Interface Tool (developerWorks, September 2006): Read this article for an introduction to SMIT.
   
• Object Data Manager (ODM) and SMIT chapters of General Programming Concepts: Writing and Debugging Programs: Browse through this online documentation.
   
• man page for the smit command (part of the bos.man.en_US.cmds fileset): This site provides information about the flags and arguments that you can use to modify SMIT's behavior.
  
   
• Search the AIX and UNIX® library by topic:
  • System administration
  • Application development
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  • Java™ technology
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• AIX and UNIX: The AIX and UNIX developerWorks zone provides a wealth of information relating to all aspects of AIX systems administration and expanding your UNIX skills.
  
   
• New to AIX and UNIX: Visit the New to AIX and UNIX page to learn more about AIX and UNIX.
  
   
• AIX 5L Wiki: A collaborative environment for technical information related to AIX.
  
   
• Safari bookstore: Visit this e-reference library to find specific technical resources.
  
   
• developerWorks technical events and webcasts: Stay current with developerWorks technical events and webcasts.
  
   
• Podcasts: Tune in and catch up with IBM technical experts.
  
   
• Future Tech: Visit Future Tech's site to learn more about their latest offerings.