[system-administrators-guide] crony: Docs QA Feedback
stephenw
stephenw at fedoraproject.org
Fri Sep 26 16:24:05 UTC 2014
commit ead5204b91ff4376bd97dc56deed8f06399ab16e
Author: Stephen Wadeley <swadeley at redhat.com>
Date: Fri Sep 26 12:50:22 2014 +0200
crony: Docs QA Feedback
en-US/Configuring_NTP_Using_the_chrony_Suite.xml | 63 +++++++++-------------
1 files changed, 25 insertions(+), 38 deletions(-)
---
diff --git a/en-US/Configuring_NTP_Using_the_chrony_Suite.xml b/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
index b1fe1e1..efaff6d 100644
--- a/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
+++ b/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
@@ -29,7 +29,7 @@ There is a choice between the daemons <systemitem class="daemon">ntpd</systemite
<itemizedlist>
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> can work well when external time references are only intermittently accessible whereas <systemitem class="daemon">ntpd</systemitem> needs regular polling of time reference to work well.
+ <systemitem class="daemon">chronyd</systemitem> can work well when external time references are only intermittently accessible, whereas <systemitem class="daemon">ntpd</systemitem> needs regular polling of time reference to work well.
</para>
</listitem>
<listitem>
@@ -49,7 +49,7 @@ There is a choice between the daemons <systemitem class="daemon">ntpd</systemite
</listitem>
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> in the default configuration never steps the time after the clock has been synchronized at system start, in order not to upset other running programs. <systemitem class="daemon">ntpd</systemitem> can be configured to never step the time too, but it has to use a different means of adjusting the clock, which has some disadvantages.
+ In the default configuration, <systemitem class="daemon">chronyd</systemitem> never steps the time after the clock has been synchronized at system start, in order not to upset other running programs. <systemitem class="daemon">ntpd</systemitem> can be configured to never step the time too, but it has to use a different means of adjusting the clock, which has some disadvantages.
</para>
</listitem>
<listitem>
@@ -66,7 +66,7 @@ Things <systemitem class="daemon">chronyd</systemitem> can do that <systemitem c
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> provides support for isolated networks where the only method of time correction is manual entry. For example, by the administrator looking at a clock. <systemitem class="daemon">chronyd</systemitem> can look at the errors corrected at different updates to estimate the rate at which the computer gains or loses time, and use this estimate to trim the computer clock subsequently.
+ <systemitem class="daemon">chronyd</systemitem> provides support for isolated networks where the only method of time correction is manual entry. For example, by the administrator looking at a clock. <systemitem class="daemon">chronyd</systemitem> can examine the errors corrected at different updates to estimate the rate at which the computer gains or loses time, and use this estimate to trim the computer clock subsequently.
</para>
</listitem>
<listitem>
@@ -121,13 +121,13 @@ Things <systemitem class="daemon">ntpd</systemitem> can do that <systemitem clas
<section id="sect-Understanding_chronyc">
<title>Understanding chronyc</title>
<para>
- The <application>chrony</application> daemon, <systemitem class="daemon">chronyd</systemitem>, can be controlled by the command line utility <application>chronyc</application>. This utility provides a command prompt which allows entering of a number of commands to make changes to <systemitem class="daemon">chronyd</systemitem>. The default configuration is for <systemitem class="daemon">chronyd</systemitem> to only accept commands from a local instance of <application>chronyc</application>, but <application>chronyc</application> can be used to alter the configuration so that <systemitem class="daemon">chronyd</systemitem> will allow external control. That is to say, <application>chronyc</application> can be run remotely after first configuring <systemitem class="daemon">chronyd</systemitem> to accept remote connections. The <systemitem class="protocol">IP</systemitem> addresses allowed to connect to <systemitem class="daemon">chronyd</systemitem> should be tightly control
led.</para>
+ The <application>chrony</application> daemon, <systemitem class="daemon">chronyd</systemitem>, can be controlled by the command line utility <application>chronyc</application>. This utility provides a command prompt which allows entering of a number of commands to make changes to <systemitem class="daemon">chronyd</systemitem>. The default configuration is for <systemitem class="daemon">chronyd</systemitem> to only accept commands from a local instance of <application>chronyc</application>, but <application>chronyc</application> can be used to alter the configuration so that <systemitem class="daemon">chronyd</systemitem> will allow external control. <application>chronyc</application> can be run remotely after first configuring <systemitem class="daemon">chronyd</systemitem> to accept remote connections. The <systemitem class="protocol">IP</systemitem> addresses allowed to connect to <systemitem class="daemon">chronyd</systemitem> should be tightly controlled.</para>
</section>
<section id="sect-Understanding_the_chrony_configuration_commands">
<title>Understanding the chrony Configuration Commands</title>
<para>
- The default configuration file for <systemitem class="daemon">chronyd</systemitem> is <filename>/etc/chrony.conf</filename>. The <option>-f</option> option can be used to specify an alternate configuration file path. See the <systemitem class="daemon">chronyd</systemitem> man page for further options. For a complete list of the directives that can be used see <ulink url="http://chrony.tuxfamily.org/manual.html#Configuration-file"><citetitle pubwork="webpage">http://chrony.tuxfamily.org/manual.html#Configuration-file</citetitle></ulink>. We present here a selection of configuration options:
+ The default configuration file for <systemitem class="daemon">chronyd</systemitem> is <filename>/etc/chrony.conf</filename>. The <option>-f</option> option can be used to specify an alternate configuration file path. See the <systemitem class="daemon">chronyd</systemitem> man page for further options. For a complete list of the directives that can be used see <ulink url="http://chrony.tuxfamily.org/manual.html#Configuration-file"><citetitle pubwork="webpage">http://chrony.tuxfamily.org/manual.html#Configuration-file</citetitle></ulink>. Below is a selection of configuration options:
<variablelist>
<varlistentry>
<term>Comments</term>
@@ -175,7 +175,7 @@ Optionally specify a host, subnet, or network from which to allow <systemitem cl
<term>cmdallow</term>
<listitem>
<para>
- This is similar to the <command>allow</command> directive (see section <command>allow</command>), except that it allows control access (rather than <systemitem class="protocol">NTP</systemitem> client access) to a particular subnet or host. (By <quote>control access</quote> is meant that <application>chronyc</application> can be run on those hosts and successfully connect to <systemitem class="daemon">chronyd</systemitem> on this computer.) The syntax is identical. There is also a <command>cmddeny</command> all directive with similar behavior to the <command>cmdallow</command> all directive.</para>
+ This is similar to the <command>allow</command> directive (see section <command>allow</command>), except that it allows control access (rather than <systemitem class="protocol">NTP</systemitem> client access) to a particular subnet or host. (By <quote>control access</quote> is meant that <application>chronyc</application> can be run on those hosts and successfully connect to <systemitem class="daemon">chronyd</systemitem> on this computer.) The syntax is identical. There is also a <command>cmddeny all</command> directive with similar behavior to the <command>cmdallow all</command> directive.</para>
</listitem>
</varlistentry>
@@ -203,7 +203,7 @@ Optionally specify a host, subnet, or network from which to allow <systemitem cl
<para>
An example of the command is:
<screen>local stratum 10</screen>
-A large value of 10 indicates that the clock is so many hops away from a reference clock that its time is fairly unreliable. Put another way, if the computer ever has access to another computer which is ultimately synchronized to a reference clock, it will almost certainly be at a stratum less than 10. Therefore, the choice of a high value like 10 for the <command>local</command> command prevents the machine’s own time from ever being confused with real time, were it ever to leak out to clients that have visibility of real servers.</para>
+A large value of 10 indicates that the clock is so many hops away from a reference clock that its time is unreliable. If the computer ever has access to another computer which is ultimately synchronized to a reference clock, it will almost certainly be at a stratum less than 10. Therefore, the choice of a high value like 10 for the <command>local</command> command prevents the machine’s own time from ever being confused with real time, were it ever to leak out to clients that have visibility of real servers.</para>
</listitem>
</varlistentry>
<varlistentry>
@@ -261,7 +261,7 @@ A large value of 10 indicates that the clock is so many hops away from a referen
</listitem>
</varlistentry>
</variablelist>
-
+
@@ -318,9 +318,9 @@ After the first clock update, <systemitem class="daemon">chronyd</systemitem> wi
<para>
One of <systemitem class="daemon">chronyd</systemitem>'s tasks is to work out how fast or slow the computer’s clock runs relative to its reference sources. In addition, it computes an estimate of the error bounds around the estimated value.
-If the range of error is too large, it probably indicates that the measurements have not settled down yet, and that the estimated gain or loss rate is not very reliable.
+If the range of error is too large, it indicates that the measurements have not settled down yet, and that the estimated gain or loss rate is not very reliable.
-The <command>maxupdateskew</command> parameter allows the threshold for determining whether an estimate may be so unreliable that it should not be used. By default, the threshold is 1000 ppm.
+The <command>maxupdateskew</command> parameter is the threshold for determining whether an estimate is too unreliable to be used. By default, the threshold is 1000 ppm.
The format of the syntax is:
@@ -360,7 +360,7 @@ The format of the syntax is:
<para>
The format of the syntax is:
<screen>stratumweight <replaceable>dist-in-seconds</replaceable></screen>
-By default, <replaceable>dist-in-seconds</replaceable> is 1 second. This usually means that sources with lower stratum will be preferred to sources with higher stratum even when their distance is significantly worse. Setting <command>stratumweight</command> to 0 makes <systemitem class="daemon">chronyd</systemitem> ignore stratum when selecting the source.
+By default, <replaceable>dist-in-seconds</replaceable> is 1 second. This means that sources with lower stratum are usually preferred to sources with higher stratum even when their distance is significantly worse. Setting <command>stratumweight</command> to 0 makes <systemitem class="daemon">chronyd</systemitem> ignore stratum when selecting the source.
</para>
</listitem>
</varlistentry>
@@ -375,7 +375,7 @@ The format of the syntax is:
<screen>rtcfile /var/lib/chrony/rtc</screen>
-<systemitem class="daemon">chronyd</systemitem> saves information in this file when it exits and when the <command>writertc</command> command is issued in <application>chronyc</application>. The information saved is the RTC’s error at some epoch, that epoch (in seconds since January 1 1970), and the rate at which the RTC gains or loses time. Not all real-time clocks are supported as their code is system-specific. Note that if this directive is used then real-time clock should not be manually adjusted as this would interfere with <application>chrony</application>'s need to measure the rate at which the real-time clock drifts if it was adjusted at random intervals.
+<systemitem class="daemon">chronyd</systemitem> saves information in this file when it exits and when the <command>writertc</command> command is issued in <application>chronyc</application>. The information saved is the RTC’s error at some epoch, that epoch (in seconds since January 1 1970), and the rate at which the RTC gains or loses time. Not all real-time clocks are supported as their code is system-specific. Note that if this directive is used then the real-time clock should not be manually adjusted as this would interfere with <application>chrony</application>'s need to measure the rate at which the real-time clock drifts if it was adjusted at random intervals.
</para>
</listitem>
</varlistentry>
@@ -689,7 +689,7 @@ This indicates the mode of the source. <literal>^</literal> means a server, <lit
<term>S</term>
<listitem>
<para>
-This column indicates the state of the sources. <quote>*</quote> indicates the source to which <systemitem class="daemon">chronyd</systemitem> is currently synchronized. <quote>+</quote> indicates acceptable sources which are combined with the selected source. <quote>-</quote> indicates acceptable sources which are excluded by the combining algorithm. <quote>?</quote> indicates sources to which connectivity has been lost or whose packets do not pass all tests. <quote>x</quote> indicates a clock which <systemitem class="daemon">chronyd</systemitem> thinks is is a falseticker (that is to say, its time is inconsistent with a majority of other sources). <quote>~</quote> indicates a source whose time appears to have too much
+This column indicates the state of the sources. <quote>*</quote> indicates the source to which <systemitem class="daemon">chronyd</systemitem> is currently synchronized. <quote>+</quote> indicates acceptable sources which are combined with the selected source. <quote>-</quote> indicates acceptable sources which are excluded by the combining algorithm. <quote>?</quote> indicates sources to which connectivity has been lost or whose packets do not pass all tests. <quote>x</quote> indicates a clock which <systemitem class="daemon">chronyd</systemitem> thinks is a <firstterm>falseticker</firstterm> ( its time is inconsistent with a majority of other sources). <quote>~</quote> indicates a source whose time appears to have too much
variability. The <quote>?</quote> condition is also shown at start-up, until at least 3 samples have been gathered from it.</para>
</listitem>
</varlistentry>
@@ -723,7 +723,7 @@ This shows the stratum of the source, as reported in its most recently received
<term>Reach</term>
<listitem>
<para>
- This shows the source’s reachability register printed as octal number. The register has 8 bits and is updated on every received or missed packet from the source. A value of 377 indicates that a valid reply was received for all from the last eight transmissions.
+ This shows the source’s reach register printed as an octal number. The register has 8 bits and is updated on every received or missed packet from the source. A value of 377 indicates that a valid reply was received for all of the last eight transmissions.
</para>
</listitem>
</varlistentry>
@@ -755,7 +755,7 @@ This shows the stratum of the source, as reported in its most recently received
The optional argument <option>-v</option> can be specified, meaning verbose. In this case, extra caption lines are shown as a reminder of the meanings of the columns.
<screen>~]$ <command>chronyc sourcestats</command>
-
+
210 Number of sources = 1
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
@@ -858,7 +858,7 @@ Where <replaceable>commandkey-password</replaceable> is the command key or passw
<section id="sect-Setting_up_chrony_for_different_environments">
<title>Setting Up chrony for Different Environments</title>
-
+
<section id="sect-Setting_up_chrony_for_a_system_which_is_infrequently_connected">
<title>Setting Up chrony for a System Which is Infrequently Connected</title>
@@ -872,20 +872,12 @@ The command key ID is generated at install time and should correspond with the <
</para>
<para>
- <orderedlist>
- <listitem>
- <para>
Using your editor running as <systemitem class="username">root</systemitem>, add the addresses of four <systemitem class="protocol">NTP</systemitem> servers as follows:
- <screen>
-server 0.pool.ntp.org offline
+ <screen>server 0.pool.ntp.org offline
server 1.pool.ntp.org offline
server 2.pool.ntp.org offline
-server 3.pool.ntp.org offline
-</screen>
+server 3.pool.ntp.org offline</screen>
The <option>offline</option> option can be useful in preventing systems from trying to activate connections. The <application>chrony</application> daemon will wait for <application>chronyc</application> to inform it that the system is connected to the network or Internet.
- </para>
- </listitem>
- </orderedlist>
</para>
</section>
@@ -974,15 +966,15 @@ From the remote systems, the system administrator can issue commands after first
</para>
<para>
- The password or hash associated with the command key for a remote system is best obtained by <systemitem class="protocol">SSH</systemitem>. That is to say, an <systemitem class="protocol">SSH</systemitem> connection should be established to the remote machine and the ID of the command key from <filename>/etc/chrony.conf</filename> and the command key in <filename>/etc/chrony.keys</filename> memorized or stored securely for the duration of the session.
+ The password or hash associated with the command key for a remote system is best obtained by <systemitem class="protocol">SSH</systemitem>. An <systemitem class="protocol">SSH</systemitem> connection should be established to the remote machine and the ID of the command key from <filename>/etc/chrony.conf</filename> and the command key in <filename>/etc/chrony.keys</filename> memorized or stored securely for the duration of the session.
</para>
- </section>
+ </section>
</section>
-
+
<!--Topics, Reference-->
<section id="sect-additional_resources">
-
+
<title>Additional Resources</title>
<para>
The following sources of information provide additional resources regarding <application>chrony</application>.
@@ -1024,14 +1016,14 @@ From the remote systems, the system administrator can issue commands after first
</itemizedlist>
</section>
-<section id="s2-chrony_Useful_Websites">
- <title>Useful Websites</title>
+<section id="s2-chrony_Online_Documentation">
+ <title>Online Documentation</title>
<variablelist>
<varlistentry>
<term><ulink url="http://chrony.tuxfamily.org/manual.html"/></term>
<listitem>
<para>
- The on-line user guide for <application>chrony</application>.
+ The online user guide for <application>chrony</application>.
</para>
</listitem>
</varlistentry>
@@ -1041,8 +1033,3 @@ From the remote systems, the system administrator can issue commands after first
</section>
</chapter>
-
-
-
-
-
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