118 lines
3.1 KiB
HTML
118 lines
3.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of E2MMPSTATUS</TITLE>
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</HEAD><BODY>
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<H1>E2MMPSTATUS</H1>
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Section: Maintenance Commands (8)<BR>Updated: January 2020<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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e2mmpstatus - Check MMP status of an ext4 filesystem
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>e2mmpstatus</B> [<B>-i</B>]
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<<I>filesystem</I>>
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<A NAME="lbAD"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><B>-i</B>
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<DD>
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prints out the MMP information rather than check it.
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</DL>
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<A NAME="lbAE"> </A>
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<H2>DESCRIPTION</H2>
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<B>e2mmpstatus</B>
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is used to check Multiple-Mount Protection (MMP) status of an ext4
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filesystem with the
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<B>mmp</B>
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feature enabled. The specified
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<I>filesystem</I>
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can be a device name (e.g.
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<I>/dev/hdc1</I>, <I>/dev/sdb2</I>),
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or an ext4 filesystem label or UUID, for example
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<B>UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd</B>
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or
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<B>LABEL=root</B>.
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By default, the
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<B>e2mmpstatus</B>
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program checks whether it is safe to mount the filesystem without taking
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the risk of mounting it more than once.
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<P>
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MMP (multiple-mount protection) is a feature that adds protection against
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the filesystem being modified simultaneously by more than one node.
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It is NOT safe to mount a filesystem when one of the following conditions
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is true:
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<BR>
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<TT> </TT>1. e2fsck is running on the filesystem.<BR>
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<BR>
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<TT> </TT>2. the filesystem is in use by another node.<BR>
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<BR>
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<TT> </TT>3. The MMP block is corrupted or cannot be read for some reason.<BR>
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<BR>
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The
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<B>e2mmpstatus</B>
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program might wait for some time to see whether the MMP block is being
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updated by any node during this period. The time taken depends on how
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frequently the MMP block is being written by the other node.
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<A NAME="lbAF"> </A>
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<H2>EXIT CODE</H2>
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The exit code returned by
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<B>e2mmpstatus</B>
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is 0 when it is safe to mount the filesystem, 1 when the MMP block shows
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the filesystem is in use on another node and it is NOT safe to mount
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the filesystem, and 2 if some other failure occurred that prevents the
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check from properly detecting the current MMP status.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?8+dumpe2fs">dumpe2fs</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+e2fsck">e2fsck</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?5+fstab">fstab</A></B>(5),
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<B><A HREF="/cgi-bin/man/man2html?8+fsck">fsck</A></B>(8),
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="2"><A HREF="#lbAB">NAME</A><DD>
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<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="4"><A HREF="#lbAD">OPTIONS</A><DD>
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<DT id="5"><A HREF="#lbAE">DESCRIPTION</A><DD>
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<DT id="6"><A HREF="#lbAF">EXIT CODE</A><DD>
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<DT id="7"><A HREF="#lbAG">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:12 GMT, March 31, 2021
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</BODY>
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</HTML>
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