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>13.5. Removing an Old Disk</H1
><P
>&#13; Say you have an old IDE drive on /dev/hdb. You want to remove that
old disk but a lot of files are on it.
</P
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>Backup Your System</B
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>&#13; You should always backup your system before attempting a pvmove
operation.
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NAME="AEN1272"
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>13.5.1. Distributing Old Extents to Existing Disks in Volume Group</H2
><P
>&#13; If you have enough free extents on the other disks in the volume
group, you have it easy. Simply run
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>&#13;<B
CLASS="command"
># pvmove /dev/hdb</B
>
<TT
CLASS="computeroutput"
>pvmove -- moving physical extents in active volume group "dev"
pvmove -- WARNING: moving of active logical volumes may cause data loss!</TT
>
<TT
CLASS="prompt"
>pvmove -- do you want to continue? [y/n]</TT
> y
<TT
CLASS="computeroutput"
>pvmove -- 249 extents of physical volume "/dev/hdb" successfully moved</TT
>
</PRE
></FONT
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>
This will move the allocated physical extents from /dev/hdb onto
the rest of the disks in the volume group.
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>pvmove</B
> is Slow</B
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><P
>&#13; Be aware that pvmove is quite slow as it has to copy the
contents of a disk block by block to one or more disks. If you
want more steady status reports from pvmove, use the
<TT
CLASS="option"
>-v</TT
> flag.
</P
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><H3
CLASS="sect3"
><A
NAME="AEN1285"
></A
>13.5.1.1. Remove the unused disk</H3
><P
>&#13; We can now remove the old IDE disk from the volume group.
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><PRE
CLASS="screen"
>&#13;<B
CLASS="command"
># vgreduce dev /dev/hdb</B
>
<TT
CLASS="computeroutput"
>vgreduce -- doing automatic backup of volume group "dev"
vgreduce -- volume group "dev" successfully reduced by physical volume:
vgreduce -- /dev/hdb</TT
>
</PRE
></FONT
></TD
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>
The drive can now be either physically removed when the
machine is next powered down or reallocated to other users.
</P
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><H2
CLASS="sect2"
><A
NAME="AEN1291"
></A
>13.5.2. Distributing Old Extents to a New Replacement Disk</H2
><P
>&#13; If you do not have enough free physical extents to distribute
the old physical extents to, you will have to add a disk to the
volume group and move the extents to it.
</P
><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN1294"
></A
>13.5.2.1. Prepare the disk</H3
><P
>&#13; First, you need to pvcreate the new disk to make it available
to LVM. In this recipe we show that you don't need to
partition a disk to be able to use it.
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>&#13;<B
CLASS="command"
># pvcreate /dev/sdf</B
>
<TT
CLASS="computeroutput"
>pvcreate -- physical volume "/dev/sdf" successfully created</TT
>
</PRE
></FONT
></TD
></TR
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>
</P
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CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN1300"
></A
>13.5.2.2. Add it to the volume group</H3
><P
>&#13; As developers use a lot of disk space this is a good volume
group to add it into.
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><PRE
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>&#13;<B
CLASS="command"
># vgextend dev /dev/sdf</B
>
<TT
CLASS="computeroutput"
>vgextend -- INFO: maximum logical volume size is 255.99 Gigabyte
vgextend -- doing automatic backup of volume group "dev"
vgextend -- volume group "dev" successfully extended</TT
>
</PRE
></FONT
></TD
></TR
></TABLE
>
</P
></DIV
><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN1306"
></A
>13.5.2.3. Move the data</H3
><P
>&#13; Next we move the data from the old disk onto the new one.
Note that it is not necessary to unmount the file system
before doing this. Although it is *highly* recommended that
you do a full backup before attempting this operation in case
of a power outage or some other problem that may interrupt
it. The pvmove command can take a considerable amount of time
to complete and it also exacts a performance hit on the two
volumes so, although it isn't necessary, it is advisable to
do this when the volumes are not too busy.
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><PRE
CLASS="screen"
>&#13;<B
CLASS="command"
># pvmove /dev/hdb /dev/sdf</B
>
<TT
CLASS="computeroutput"
>pvmove -- moving physical extents in active volume group "dev"
pvmove -- WARNING: moving of active logical volumes may cause data loss!</TT
>
<TT
CLASS="prompt"
>pvmove -- do you want to continue? [y/n]</TT
> y
<TT
CLASS="computeroutput"
>pvmove -- 249 extents of physical volume "/dev/hdb" successfully moved</TT
>
</PRE
></FONT
></TD
></TR
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>
</P
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><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN1314"
></A
>13.5.2.4. Remove the unused disk</H3
><P
>&#13; We can now remove the old IDE disk from the volume group.
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><FONT
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><PRE
CLASS="screen"
>&#13;<B
CLASS="command"
># vgreduce dev /dev/hdb</B
>
<TT
CLASS="computeroutput"
>vgreduce -- doing automatic backup of volume group "dev"
vgreduce -- volume group "dev" successfully reduced by physical volume:
vgreduce -- /dev/hdb</TT
>
</PRE
></FONT
></TD
></TR
></TABLE
>
The drive can now be either physically removed when the
machine is next powered down or reallocated to some other
users.
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