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-rw-r--r--system/doc/design_principles/appup_cookbook.xml61
-rw-r--r--system/doc/design_principles/release_handling.xml52
2 files changed, 92 insertions, 21 deletions
diff --git a/system/doc/design_principles/appup_cookbook.xml b/system/doc/design_principles/appup_cookbook.xml
index bc61578953..798b23d847 100644
--- a/system/doc/design_principles/appup_cookbook.xml
+++ b/system/doc/design_principles/appup_cookbook.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>2003</year><year>2009</year>
+ <year>2003</year><year>2011</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -603,25 +603,60 @@ code_change(_OldVsn, State, port) ->
</section>
<section>
- <title>Emulator Restart</title>
- <p>If the emulator can or should be restarted, the very simple
- <c>.relup</c> file can be created manually:</p>
+ <title>Emulator Restart and Upgrade</title>
+ <p>There are two upgrade instructions that will restart the emulator:</p>
+ <taglist>
+ <tag><c>restart_new_emulator</c></tag>
+ <item>Intended for when erts, kernel, stdlib or sasl is
+ upgraded. It is automatically added when the relup file is
+ generated by <c>systools:make_relup/3,4</c>. It is executed
+ before all other upgrade instructions. See
+ <seealso marker="release_handling#restart_new_emulator_instr">Release
+ Handling</seealso> for more information about this
+ instruction.</item>
+ <tag><c>restart_emulator</c></tag>
+ <item>Used when a restart of the emulator is required after all
+ other upgrade instructions are executed. See
+ <seealso marker="release_handling#restart_emulator_instr">Release
+ Handling</seealso> for more information about this
+ instruction.</item>
+ </taglist>
+
+ <p>If an emulator restart is necessary and no upgrade instructions
+ are needed, i.e. if the restart itself is enough for the
+ upgraded applications to start running the new versions, a very
+ simple <c>.relup</c> file can be created manually:</p>
<code type="none">
{"B",
[{"A",
[],
- [restart_new_emulator]}],
+ [restart_emulator]}],
[{"A",
[],
- [restart_new_emulator]}]
+ [restart_emulator]}]
}.</code>
- <p>This way, the release handler framework with automatic packing
- and unpacking of release packages, automatic path updates etc. can
- be used without having to specify <c>.appup</c> files.</p>
- <p>If some transformation of persistent data, for example database
- contents, needs to be done before installing the new release
- version, instructions for this can be added to the <c>.relup</c>
- file as well.</p>
+ <p>In this case, the release handler framework with automatic
+ packing and unpacking of release packages, automatic path
+ updates etc. can be used without having to specify <c>.appup</c>
+ files.</p>
+ </section>
+
+ <section>
+ <title>Emulator Upgrade from pre OTP R15</title>
+ <p>From OTP R15, an emulator upgrade is performed by restarting
+ the emulator with new versions of the core applications
+ (<c>kernel</c>, <c>stdlib</c> and <c>sasl</c>) before loading code
+ and running upgrade instruction for other applications. For this
+ to work, the release to upgrade from must includes OTP R15 or
+ later. For the case where the release to upgrade from includes an
+ earlier emulator version, <c>systools:make_relup</c> will create a
+ backwards compatible relup file. This means that all upgrade
+ instructions will be executed before the emulator is
+ restarted. The new application code will therefore be loaded into
+ the old emulator. If the new code is compiled with the new
+ emulator, there might be cases where the beam format has changed
+ and beam files can not be loaded. To overcome this problem, the
+ new code should be compiled with the old emulator.</p>
</section>
</chapter>
diff --git a/system/doc/design_principles/release_handling.xml b/system/doc/design_principles/release_handling.xml
index 1d62c242c0..8ed36f3c56 100644
--- a/system/doc/design_principles/release_handling.xml
+++ b/system/doc/design_principles/release_handling.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>2003</year><year>2009</year>
+ <year>2003</year><year>2011</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -313,18 +313,35 @@
</section>
<section>
+ <marker id="restart_new_emulator_instr"></marker>
<title>restart_new_emulator (low-level)</title>
<p>This instruction is used when changing to a new emulator
- version, or if a system reboot is needed for some other reason.
- Requires that the system is started with heart beat
+ version, or when any of the core applications kernel, stdlib
+ or sasl is upgraded. If a system reboot is needed for some
+ other reason, the <c>restart_emulator</c> instruction should
+ be used instead.</p>
+ <p>Requires that the system is started with heart beat
monitoring, see <c>erl(1)</c> and <c>heart(3)</c>.</p>
- <p>When the release handler encounters the instruction, it shuts
- down the current emulator by calling <c>init:reboot()</c>, see
+ <p>The <c>restart_new_emulator</c> instruction shall always be
+ the very first instruction in a relup. If the relup is
+ generated by <c>systools:make_relup/3,4</c> this is
+ automatically ensured.</p>
+ <p>When the release handler encounters the instruction, it first
+ generates a temporary boot file, which starts the new versions
+ of the emulator and the core applications. Then it shuts down
+ the current emulator by calling <c>init:reboot()</c>, see
<c>init(3)</c>. All processes are terminated gracefully and
the system can then be rebooted by the heart program, using
- the new release version. This new version must still be made
- permanent when the new emulator is up and running. Otherwise,
- the old version is used in case of a new system reboot.</p>
+ the temporary boot file. After the reboot, the rest of the
+ relup instructions are executed. This is done as a part of the
+ boot script.</p>
+ <p>An info report is written when the upgrade is completed. To
+ programatically find out if the upgrade is complete,
+ call <c>release_handler:which_releases/0</c> and check if the
+ expected release has status <c>current</c>.</p>
+ <p>The new version must be made permanent when the new emulator
+ is up and running. Otherwise, the old version will be used in
+ case of a new system reboot.</p>
<p>On UNIX, the release handler tells the heart program which
command to use to reboot the system. Note that the environment
variable <c>HEART_COMMAND</c>, normally used by the heart
@@ -333,6 +350,25 @@
by using the SASL configuration parameter <c>start_prg</c>, see
<c>sasl(6)</c>.</p>
</section>
+
+ <section>
+ <marker id="restart_emulator_instr"></marker>
+ <title>restart_emulator (low-level)</title>
+ <p>This instruction is not related to upgrades of erts or any of
+ the core applications. It can be used by any application to
+ force a restart of the emulator after all upgrade instructions
+ are executed.</p>
+ <p>There can only be one <c>restart_emulator</c> instruction in
+ a relup script, and it shall always be placed at the end. If
+ the relup is generated by <c>systools:make_relup/3,4</c> this
+ is automatically ensured.</p>
+ <p>When the release handler encounters the instruction, it shuts down
+ the emulator by calling <c>init:reboot()</c>, see
+ <c>init(3)</c>. All processes are terminated gracefully and
+ the system can then be rebooted by the heart program using the
+ new release version. No more upgrade instruction will be
+ executed after the restart.</p>
+ </section>
</section>
<section>