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>13.1. Setting up LVM on three SCSI disks</H1
><P
> For this recipe, the setup has three SCSI disks that will be put
into a logical volume using LVM. The disks are at /dev/sda,
/dev/sdb, and /dev/sdc.
</P
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><H2
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>13.1.1. Preparing the disks</H2
><P
> Before you can use a disk in a volume group you will have to
prepare it:
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> </TD
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><P
> <STRONG
> The following will destroy any data on /dev/sda, /dev/sdb,
and /dev/sdc
</STRONG
>
</P
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><P
> Run pvcreate on the disks
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> <B
CLASS="command"
># pvcreate /dev/sda
# pvcreate /dev/sdb
# pvcreate /dev/sdc</B
>
</PRE
></FONT
></TD
></TR
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>
This creates a volume group descriptor area (VGDA) at the start
of the disks.
</P
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><H2
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><A
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>13.1.2. Setup a Volume Group</H2
><P
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><LI
><P
> Create a volume group
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> <B
CLASS="command"
># vgcreate my_volume_group /dev/sda /dev/sdb /dev/sdc/</B
>
</PRE
></FONT
></TD
></TR
></TABLE
>
</P
></LI
><LI
><P
> Run vgdisplay to verify volume group
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> <B
CLASS="command"
># vgdisplay</B
>
<TT
CLASS="computeroutput"
># vgdisplay
--- Volume Group ---
VG Name my_volume_group
VG Access read/write
VG Status available/resizable
VG # 1
MAX LV 256
Cur LV 0
Open LV 0
MAX LV Size 255.99 GB
Max PV 256
Cur PV 3
Act PV 3
VG Size 1.45 GB
PE Size 4 MB
Total PE 372
Alloc PE / Size 0 / 0
Free PE / Size 372/ 1.45 GB
VG UUID nP2PY5-5TOS-hLx0-FDu0-2a6N-f37x-0BME0Y</TT
>
</PRE
></FONT
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>
The most important things to verify are that the first
three items are correct and that the VG Size item is the
proper size for the amount of space in all four of your
disks.
</P
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><H2
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><A
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></A
>13.1.3. Creating the Logical Volume</H2
><P
> If the volume group looks correct, it is time to create a
logical volume on top of the volume group.
</P
><P
> You can make the logical volume any size you like. (It is
similar to a partition on a non LVM setup.) For this example we
will create just a single logical volume of size 1GB on the
volume group. We will not use striping because it is not
currently possible to add a disk to a stripe set after the
logical volume is created.
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> <B
CLASS="command"
># lvcreate -L1G -nmy_logical_volume my_volume_group</B
>
<TT
CLASS="computeroutput"
>lvcreate -- doing automatic backup of "my_volume_group"
lvcreate -- logical volume "/dev/my_volume_group/my_logical_volume" successfully created</TT
>
</PRE
></FONT
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>
</P
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><DIV
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><H2
CLASS="sect2"
><A
NAME="AEN1085"
></A
>13.1.4. Create the File System</H2
><P
> Create an ext2 file system on the logical volume
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> <B
CLASS="command"
># mke2fs /dev/my_volume_group/my_logical_volume</B
>
<TT
CLASS="computeroutput"
>mke2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
131072 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
9 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Writing inode tables: done
Writing superblocks and filesystem accounting information: done</TT
>
</PRE
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>
</P
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><H2
CLASS="sect2"
><A
NAME="AEN1091"
></A
>13.1.5. Test the File System</H2
><P
> Mount the logical volume and check to make sure everything looks
correct
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> <B
CLASS="command"
># mount /dev/my_volume_group/my_logical_volume /mnt
# df</B
>
<TT
CLASS="computeroutput"
>Filesystem 1k-blocks Used Available Use% Mounted on
/dev/hda1 1311552 628824 616104 51% /
/dev/my_volume_group/my_logical_volume
1040132 20 987276 0% /mnt</TT
>
</PRE
></FONT
></TD
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>
</P
><P
> If everything worked properly, you should now have a logical
volume with and ext2 file system mounted at
<TT
CLASS="filename"
>/mnt</TT
>.
</P
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