Add more notes for 2015-12

Signed-off-by: Alan Orth <alan.orth@gmail.com>

public/2015-12/index.html

@@ -95,6 +95,43 @@
 <ul>
 <li>I had used lrzip once, but it needs more memory and is harder to use as it requires the lrztar wrapper</li>
 <li>Need to remember to go check if everything is ok in a few days and then change CGSpace</li>
+<li>CGSpace went down again (due to PostgreSQL idle connections of course)</li>
+<li>Current database settings for DSpace are <code>db.maxconnections = 30</code> and <code>db.maxidle = 8</code>, yet idle connections are exceeding this:</li>
+</ul>
+
+<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep cgspace | grep -c idle
+39
+</code></pre>
+
+<ul>
+<li>I restarted PostgreSQL and Tomcat and it&rsquo;s back</li>
+<li>On a related note of why CGSpace is so slow, I decided to finally try the <code>pgtune</code> script to tune the postgres settings:</li>
+</ul>
+
+<pre><code># apt-get install pgtune
+# pgtune -i /etc/postgresql/9.3/main/postgresql.conf -o postgresql.conf-pgtune
+# mv /etc/postgresql/9.3/main/postgresql.conf /etc/postgresql/9.3/main/postgresql.conf.orig 
+# mv postgresql.conf-pgtune /etc/postgresql/9.3/main/postgresql.conf
+</code></pre>
+
+<ul>
+<li>It introduced the following new settings:</li>
+</ul>
+
+<pre><code>default_statistics_target = 50
+maintenance_work_mem = 480MB
+constraint_exclusion = on
+checkpoint_completion_target = 0.9
+effective_cache_size = 5632MB
+work_mem = 48MB
+wal_buffers = 8MB
+checkpoint_segments = 16
+shared_buffers = 1920MB
+max_connections = 80
+</code></pre>
+
+<ul>
+<li>Now I need to go read PostgreSQL docs about these options, and watch memory settings in munin etc</li>
 </ul>
 
   </section>