Commit 942fab72 authored by Marcin Siodelski's avatar Marcin Siodelski
Browse files

[#78,!85] Added section to the User Guide about sync-page-limit parameter.

parent 3f80f943
...@@ -975,7 +975,29 @@ ...@@ -975,7 +975,29 @@
hooks library configuration is designed to maximize the administration hooks library configuration is designed to maximize the administration
flexibility. flexibility.
</para> </para>
</section>
<section xml:id="ha-syncing-page-limit">
<title>Controlling Lease Page Size Limit</title>
<para>HA enabled server initiates synchronization of the lease
database after down time or upon receiving <command>ha-sync</command>
command. The server uses commands described in
<xref linkend="lease-get-page-cmds"/> to fetch leases from the
partner server (lease queries). The size of the results page
(maximum number of leases to be returned in a single response to one
of these commands) can be controlled via HA hooks library configuration.
Increasing the page size decreases the number of lease queries sent to
the partner server, but it causes the partner server to generate
larger responses, which lengthens transmission time as well as
memory and CPU utilization on both servers. Decreasing the
page size helps to decrease resources utilization but requires
more lease queries to be issued to fetch the entire lease
database.</para>
<para>The default value of the <command>sync-page-limit</command>
controlling the page size is 10000. This means that the entire
lease database can be fetched with a single command if the
size of this database is equal or lower than 10000.
</para>
</section> </section>
<section xml:id="ha-syncing-timeouts"> <section xml:id="ha-syncing-timeouts">
...@@ -1330,10 +1352,10 @@ ...@@ -1330,10 +1352,10 @@
The <command>max-period</command> parameter specifies the maximum The <command>max-period</command> parameter specifies the maximum
duration (in seconds) for which the DHCP service should be disabled. duration (in seconds) for which the DHCP service should be disabled.
If the DHCP service is successfully disabled, the synchronizing If the DHCP service is successfully disabled, the synchronizing
server will fetch leases from the remote server by issuing the server will fetch leases from the remote server by issuing one or
<command>lease4-get-all</command> command. When the lease database more <command>lease4-get-page</command> commands. When the lease
synchronization is complete, the synchronizing server sends the database synchronization is complete, the synchronizing server sends
<command>dhcp-enable</command> to the peer to re-enable its the <command>dhcp-enable</command> to the peer to re-enable its
DHCP service. DHCP service.
</para> </para>
......
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