<HTML ><HEAD ><TITLE >Advanced Power Management</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Remote Serial Console HOWTO" HREF="index.html"><LINK REL="UP" TITLE="Bugs and annoyances" HREF="bugs.html"><LINK REL="PREVIOUS" TITLE="Boot loaders are vulnerable to line noise" HREF="bugs-bootloadernoise.html"><LINK REL="NEXT" TITLE="Modems and overseas telecommunications requirements" HREF="bugs-international.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Remote Serial Console HOWTO</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="bugs-bootloadernoise.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Appendix A. Bugs and annoyances</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="bugs-international.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="BUGS-APM" ></A >A.10. <SPAN CLASS="PRODUCTNAME" >Advanced Power Management</SPAN ></H1 ><P ><SPAN CLASS="ACRONYM" >APM</SPAN > allows control of the power from software. This can be a blessing and a curse.</P ><P >The blessing is that the machine can be cleanly and totally shut down remotely. You may want to do this if the remote site is maintaining their power supply.</P ><P >The curse is that once powered down the machine will not start up again until the <B CLASS="KEYCAP" >Power</B > button is physically pressed. Some machines have a <SPAN CLASS="ACRONYM" >BIOS</SPAN > or motherboard setting to defeat this unhelpful behaviour.</P ><DIV CLASS="CAUTION" ><A NAME="CAUTION-SHUTDOWN" ></A ><P ></P ><TABLE CLASS="CAUTION" WIDTH="100%" BORDER="0" ><TR ><TD WIDTH="25" ALIGN="CENTER" VALIGN="TOP" ><IMG SRC="../images/caution.gif" HSPACE="5" ALT="Caution"></TD ><TH ALIGN="LEFT" VALIGN="CENTER" ><B >Errors when typing <B CLASS="COMMAND" >shutdown</B > are worse with <SPAN CLASS="ACRONYM" >APM</SPAN ></B ></TH ></TR ><TR ><TD > </TD ><TD ALIGN="LEFT" VALIGN="TOP" ><P >Be careful not to confuse <B CLASS="COMMAND" >shutdown -r now</B >, which cleanly reboots the machine, with <B CLASS="COMMAND" >shutdown -h now</B >, which cleanly powers down the machine. Someone will need to physically press the <B CLASS="KEYCAP" >Power</B > button if you choose wrongly.</P ></TD ></TR ></TABLE ></DIV ><P >If you are serious about remote site computing then you should investigate remote power switches from companies like <A HREF="http://www.wti.com/" TARGET="_top" >Western Telematic</A >, <A HREF="http://www.servertech.com/" TARGET="_top" >Server Technology</A > and many others. Some models include built-in terminal servers, built-in modems and <SPAN CLASS="ACRONYM" >RS-232</SPAN > lines to simulate a <SPAN CLASS="ACRONYM" >UPS</SPAN > input power failure (and thus shut the <SPAN CLASS="SYSTEMITEM" >Linux</SPAN > system down cleanly before removing power).</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="bugs-bootloadernoise.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="bugs-international.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Boot loaders are vulnerable to line noise</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="bugs.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Modems and overseas telecommunications requirements</TD ></TR ></TABLE ></DIV ></BODY ></HTML >