Logical Volume Manager (LVM). Part II

In the first part of the article about LVM I described the structure and basic configuration files. The second part will focus on  LVM configuration commands.

Create Volume Group vg01:

1. Find free disks. Useful commands:
   - ioscan-funC disk -lists the drives in the system,
   - insf-C disk -creates device files to disk (if there was),
   - bdf -list of mounted file systems (helps define engaged wheels)
   - swapinfo-d -displays the disks and filesystems, used as a swap area
   - strings/etc/lvmtab -list existing volume group and drives in them
   
   - vxdisk list -a list of drives employed in VxVM (another system/disk management).
2. Check the availability and integrity of the selected disks. For example,/dev/dsk/c0t1d0:
   
   1. diskinfo/dev/rdsk/c1t1d2 -information about the disk
   2. dd if =/dev/rdsk/c1t1d2 of =/dev/null bs = 1024 k -read the contents of a disk, a
      search for "bad blocks".
3. Prepare disks by creating them physical volumes (PV):
   pvcreate-f/dev/rdsk/c1t1d2 for slow disks, you can specify a larger timeout by adding the
   option "-t 180".
4. Create a directory and a control file (group special file):
   
   1. mkdir/dev/vg01
   2. chmod 755/dev/vg01
   3. mknod/dev/vg01/group c 64 0x010000 the control file is always character type-c
      major (major) always-64 and younger (minor) is encoded 0xhh0000, where hh is a unique
      hexadecimal number of the VG.
   4. chown-R root: sys/dev/vg01
   5. chmod 640/dev/vg01/group
5. Create A Volume Group:
   - vgcreate/dev/vg01/dev/dsk/c1t1d2 if multiple disks, then scroll through the gap. A set
    of parameters that can be set:
   -s 1-256 ( default  4 MB ) the size of the physical extent (pieces that are distributed)-p
    1-255 ( default 255 ) the maximum number of PV 
   -l 1-255 ( default 255 ) the maximum number of LV,
   -e 1-65535 (default, 1016  which corresponds to 4 GB) is the maximum number of physical
   extents on disk (physical). Is very important and is set depending on the size of the volume
   by the formula: PV size < >/< > size of the extent.
   Does not change in the future, making it impossible to add more disks larger than the original,
   in the Volume Group.
6. View VG settings command:
   - vgdisplay vg01

Now you can create the Logical volume: lvol1

1. Reserve the name:
   - lvcreate-n lvol1 vg01
2. Expand the LV to the desired size by selecting what disk in VG:
   
    lvextend-L 200/dev/vg01/lvol1/dev/dsk/c1t1d2 the key-L Specifies the size, in MB
    and the key-l specifies the size in extents. Be careful.
3. You can set additional parameters:
   - lvchange-a y | n/dev/vg01/lvol1 -resolution | ban on the use of LV.
   - lvchange-p r | w/dev/vg01/lvol1 -the right to "read-only" | " read-write when using a
     Logical Volume.
   - lvchange-r y | n | N/dev/vg01/lvol1 -options for working with "bad blocks": move the
    "bad blocks" | does not move and I/O error | disables the mechanism for the use of disk array,
    for example.
4. Show volume settings you can command: lvdisplay/dev/vg01/lvol1

You can create a Logical Volume in a single command lvcreate, immediately indicating the size,
but the above sequence of commands allows you to specify which drive of the VG will be a LV. This adds flexibility when creating.

Use Logical Volume lvol1:

• As the file system:
  
  1. newfs-F vxfs/dev/vg01/rlvol1
  2. mkdir/data
  3. mount/dev/vg01/lvol1/data
  4. vi/etc/fstab -add a file system to mount after reboot.
• As a swap area:
  
  1. swapon/dev/vg01/lvol1
  2. vi/etc/fstab -add to use after the reboot.

Before using read the documentation man: