306 lines
5.2 KiB
HTML
306 lines
5.2 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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>Sharing LVM volumes</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="Dangerous Operations"
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HREF="dangerousops.html"><LINK
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REL="PREVIOUS"
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TITLE="Restoring the VG UUIDs using uuid_fixer"
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HREF="uuidfixer.html"><LINK
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REL="NEXT"
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TITLE="Reporting Errors and Bugs"
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HREF="reportbug.html"></HEAD
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><BODY
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CLASS="sect1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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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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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="uuidfixer.html"
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ACCESSKEY="P"
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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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ALIGN="center"
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VALIGN="bottom"
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>Appendix A. Dangerous Operations</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="reportbug.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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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="sharinglvm1"
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></A
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>A.2. Sharing LVM volumes</H1
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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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CLASS="warning"
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WIDTH="100%"
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BORDER="0"
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><TR
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><TD
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WIDTH="25"
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ALIGN="CENTER"
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VALIGN="TOP"
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><IMG
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SRC="../images/warning.gif"
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HSPACE="5"
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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 is not cluster aware</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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> Be very careful doing this, LVM is not currently cluster-aware
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and it is very easy to lose all your data.
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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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><P
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>
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If you have a fibre-channel or shared-SCSI environment where more
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than one machine has physical access to a set of disks then you can
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use LVM to divide these disks up into logical volumes. If you want
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to share data you should really be looking at
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<A
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HREF="http://www.sistina.com/gfs"
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TARGET="_top"
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>GFS</A
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> or other
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cluster filesystems.
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</P
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><P
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> The key thing to remember when sharing volumes is that all the LVM
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administration must be done on one node only and that all other
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nodes must have LVM shut down before changing anything on the admin
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node. Then, when the changes have been made, it is necessary to
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run vgscan on the other nodes before reloading the volume groups.
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Also, unless you are running a cluster-aware filesystem (such as
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GFS) or application on the volume, only one node can mount each
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filesystem. It is up to you, as system administrator to enforce
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this, LVM will not stop you corrupting your data.
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</P
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><P
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> The startup sequence of each node is the same as for a single-node
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setup with
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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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> vgscan
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vgchange -ay
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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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in the startup scripts.
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</P
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><P
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> If you need to do <STRONG
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>any</STRONG
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> changes to
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the LVM metadata (regardless of whether it affects volumes mounted
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on other nodes) you must go through the following sequence. In the
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steps below ``admin node'' is any arbitrarily chosen node in the
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cluster.
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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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> Admin node Other nodes
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---------- -----------
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Close all Logical volumes (umount)
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vgchange -an
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<make changes, eg lvextend>
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vgscan
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vgchange -ay
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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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</P
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><DIV
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CLASS="note"
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><P
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></P
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><TABLE
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CLASS="note"
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WIDTH="100%"
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BORDER="0"
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><TR
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><TD
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WIDTH="25"
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ALIGN="CENTER"
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VALIGN="TOP"
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><IMG
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SRC="../images/note.gif"
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HSPACE="5"
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ALT="Note"></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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>VGs should be active on the admin node</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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> You do not need to, nor should you, unload the VGs on
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the admin node, so this can be the node with the highest uptime
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requirement.
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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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><P
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> I'll say it again: <STRONG
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>Be very careful doing
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this</STRONG
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>
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</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
|
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
|
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><A
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HREF="uuidfixer.html"
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ACCESSKEY="P"
|
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>Prev</A
|
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
|
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
|
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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><A
|
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HREF="reportbug.html"
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ACCESSKEY="N"
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>Next</A
|
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></TD
|
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></TR
|
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><TR
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><TD
|
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
|
>Restoring the VG UUIDs using uuid_fixer</TD
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><TD
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
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HREF="dangerousops.html"
|
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ACCESSKEY="U"
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>Up</A
|
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></TD
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>Reporting Errors and Bugs</TD
|
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></TR
|
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></TABLE
|
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></DIV
|
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></BODY
|
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></HTML
|
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> |