244 lines
3.7 KiB
HTML
244 lines
3.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>mapping modes (linear/striped)</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="LVM HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Anatomy of LVM"
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HREF="anatomy.html"><LINK
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REL="PREVIOUS"
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TITLE="Tying it all together"
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HREF="tyingittogether.html"><LINK
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REL="NEXT"
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TITLE="Snapshots"
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HREF="snapshotintro.html"></HEAD
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>LVM HOWTO</TH
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></TR
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><TD
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WIDTH="10%"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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VALIGN="bottom"
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>Chapter 3. Anatomy of LVM</TD
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><TD
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WIDTH="10%"
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VALIGN="bottom"
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="mapmode"
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></A
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>3.7. mapping modes (linear/striped)</H1
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><P
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> The administrator can choose between a couple of general strategies
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for mapping logical extents onto physical extents:
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</P
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><P
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></P
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><OL
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TYPE="1"
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><LI
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><P
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> <STRONG
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>Linear mapping</STRONG
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> will assign a
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range of PE's to an area of an LV in order eg., LE 1 - 99 map to
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PV1 and LE 100 - 347 map onto PV2.
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</P
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></LI
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><LI
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><P
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> <STRONG
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>Striped mapping</STRONG
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> will interleave
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the chunks of the logical extents across a number of physical
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volumes eg.,
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="screen"
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> 1st chunk of LE[1] -> PV1[1],
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2nd chunk of LE[1] -> PV2[1],
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3rd chunk of LE[1] -> PV3[1],
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4th chunk of LE[1] -> PV1[2],
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</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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and so on. In certain situations this strategy can
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improve the performance of the logical volume.
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<DIV
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CLASS="warning"
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><P
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></P
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><TABLE
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SRC="../images/warning.gif"
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ALT="Warning"></TD
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><TH
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ALIGN="LEFT"
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VALIGN="CENTER"
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><B
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>LVM 1 Caveat</B
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></TH
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></TR
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><TR
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><TD
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> </TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><P
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> LVs created using striping cannot be extended past
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the PVs they were originally created on in LVM 1.
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</P
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></TD
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></TR
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></TABLE
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></DIV
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>
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In LVM 2, striped LVs can be extended by concatenating
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another set of devices onto the end of the first set. So
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you can get into a situation where your LV is a 2 stripe
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set concatenated with a linear set concatenated with a 4
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stripe set. Are you confused yet?
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</P
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></LI
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></OL
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>Prev</A
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>Next</A
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WIDTH="33%"
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VALIGN="top"
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>Tying it all together</TD
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><TD
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WIDTH="34%"
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VALIGN="top"
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>Up</A
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>Snapshots</TD
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> |