262 lines
6.1 KiB
HTML
262 lines
6.1 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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>Faulty objects</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="EVMS User Guide"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="The MD region manager"
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HREF="appxmdreg.html"><LINK
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REL="PREVIOUS"
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TITLE="Active and spare objects"
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HREF="activepsareobjs.html"><LINK
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REL="NEXT"
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TITLE="Resizing MD regions"
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HREF="resizemdreg.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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>EVMS User Guide</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="activepsareobjs.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 B. The MD region manager</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="resizemdreg.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="faultobjs"
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></A
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>B.4. Faulty objects</H1
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><P
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> As discussed in the previous section, if one of the active objects in a
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RAID-1 or RAID-4/5 region has a problem, that object will be kicked out and
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the region will become degraded.
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A problem can occur with active objects in a variety of ways.
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For instance, a disk can crash, a disk can be pulled out of the
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system, a drive cable can be removed, or one or more I/Os can cause errors.
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Any of these will result in the object being kicked out and the RAID
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region becoming degraded.
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</P
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><P
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> If a disk has completely stopped working or has been removed from the
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machine, EVMS obviously will no longer recognize that disk, and it will
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not show up as part of the RAID region when running the EVMS user interfaces.
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However, if the disk is still available in the machine, EVMS will likely
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be able to recognize that the disk is assigned to the RAID region, but has
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been removed from any active service by the kernel.
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This type of disk is referred to as a faulty object.
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</P
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="remfaultyobjs"
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></A
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>B.4.1. Removing faulty objects</H2
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><P
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> Faulty objects are no longer usable by the RAID region, and should be
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removed.
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You can remove faulty objects with the "remfaulty" plug-in function
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for both RAID-1 and RAID-4/5. This operation is very similar to
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removing spare objects. After the object is removed, it will appear
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in the Available-Objects list in the EVMS user interfaces.
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</P
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><P
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> Faulty objects can be removed while the RAID region is active and in use.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="fixtempfailedobjs"
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></A
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>B.4.2. Fixing temporarily failed objects</H2
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><P
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> Sometimes a disk can have a temporary problem that causes the disk to be
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marked faulty and the RAID region to become degraded.
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For instance, a drive cable can come loose, causing the MD kernel driver
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to think the disk has disappeared.
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However, if the cable is plugged back in, the disk should be available
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for normal use.
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However, the MD kernel driver and the EVMS MD plug-in will continue to
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indicate that the disk is a faulty object because the disk might have
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missed some writes to the RAID region and would therefore be out of
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sync with the rest of the disks in the region.
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</P
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><P
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> In order to correct this situation, the faulty object should be
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removed from the RAID region (as discussed in the previous section).
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The object will then show up as an Available-Object.
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Next, that object should be added back to the RAID region as a spare
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(as discussed in <A
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HREF="activepsareobjs.html#addspareobjs"
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>Section B.3.1</A
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>. When the
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changes are saved, the MD kernel driver will activate the spare and
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sync the data and parity.
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When the sync is complete, the RAID region will be operating in its
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original, normal configuration.
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</P
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><P
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> This procedure can be accomplished while the RAID region is active and
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in use.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="markobjsfaulty"
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></A
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>B.4.3. Marking objects faulty</H2
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><P
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> EVMS provides the ability to manually mark a child of a RAID-1 or
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RAID-4/5 region as faulty.
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This has the same effect as if the object had some problem or
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caused I/O errors.
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The object will be kicked out from active service in the region, and
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will then show up as a faulty object in EVMS.
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It can then be removed from the region as discussed in the previous
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sections.
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</P
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><P
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> There are a variety of reasons why you might want to manually mark an
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object faulty.
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One example would be to test failure scenarios to learn how Linux and
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EVMS deal with the hardware failures.
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Another example would be that you want to replace one of the current
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active objects with a different object.
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To do this, you would add the new object as a spare, then mark the
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current object faulty (causing the new object to be activated and
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the data to be resynced), and finally remove the faulty object.
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</P
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><P
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> EVMS allows you to mark an object faulty in a RAID-1 region if there
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are more than one active objects in the region.
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EVMS allows you to mark an object faulty in a RAID-4/5 region if the
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region has a spare object.
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</P
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><P
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> Use the "markfaulty" plug-in function for both RAID-1 and RAID-4/5.
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This command can be used while the RAID region is active and in use.
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</P
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></DIV
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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="33%"
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ALIGN="left"
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VALIGN="top"
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HREF="activepsareobjs.html"
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ACCESSKEY="P"
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>Prev</A
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VALIGN="top"
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>Next</A
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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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>Active and spare objects</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="appxmdreg.html"
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Resizing MD regions</TD
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></TR
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