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    CC Raghavendra G, who maintains performance translators to explain
    how io-cache works.<br>
    <br>
    Pranith<br>
    <div class="moz-cite-prefix">On 08/22/2014 09:14 PM, Juan Jos&eacute;
      Pavlik Salles wrote:<br>
    </div>
    <blockquote
cite="mid:CAKCETkeN01m6E-+GSOveca7PFQLoVDLP_Mh-cyZN56EoQF9TSg@mail.gmail.com"
      type="cite">
      <div dir="ltr">Hi Ben, I also thought of that, but look at this:
        <div><br>
        </div>
        <div>
          <div>[root@gluster-client-1 gluster_vol]# echo 3 &gt;
            /proc/sys/vm/drop_caches; dd if=/mnt/gluster_vol/128
            of=/dev/null bs=1M;&nbsp;</div>
          <div>
            128+0 records in</div>
          <div>128+0 records out</div>
          <div>134217728 bytes (134 MB) copied, 6,70874 s, 20,0 MB/s</div>
          <div>[root@gluster-client-1 gluster_vol]# echo 3 &gt;
            /proc/sys/vm/drop_caches; dd if=/mnt/gluster_vol/128
            of=/dev/null bs=1M;&nbsp;</div>
          <div>128+0 records in</div>
          <div>128+0 records out</div>
          <div>134217728 bytes (134 MB) copied, 0,160485 s, 836 MB/s</div>
          <div>[root@gluster-client-1 gluster_vol]# echo 3 &gt;
            /proc/sys/vm/drop_caches; dd if=/mnt/gluster_vol/128
            of=/dev/null bs=1M;&nbsp;</div>
          <div>128+0 records in</div>
          <div>128+0 records out</div>
          <div>134217728 bytes (134 MB) copied, 0,148219 s, 906 MB/s</div>
          <div>[root@gluster-client-1 gluster_vol]#&nbsp;</div>
        </div>
        <div><br>
        </div>
        <div>even dropping kernel caches I get a really fast answer. I
          think that this is io-cache translator working on the client
          side for sure.</div>
      </div>
      <div class="gmail_extra"><br>
        <br>
        <div class="gmail_quote">2014-08-22 12:27 GMT-03:00 Ben Turner <span
            dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:bturner@redhat.com" target="_blank">bturner@redhat.com</a>&gt;</span>:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div class="HOEnZb">
              <div class="h5">----- Original Message -----<br>
                &gt; From: "Juan Jos&eacute; Pavlik Salles" &lt;<a
                  moz-do-not-send="true"
                  href="mailto:jjpavlik@gmail.com">jjpavlik@gmail.com</a>&gt;<br>
                &gt; To: <a moz-do-not-send="true"
                  href="mailto:gluster-users@gluster.org">gluster-users@gluster.org</a><br>
                &gt; Sent: Thursday, August 21, 2014 4:07:28 PM<br>
                &gt; Subject: [Gluster-users] Gluster 3.5.2 gluster, how
                does cache work?<br>
                &gt;<br>
                &gt; Hi guys, I've been reading a bit about caching in
                gluster volumes, but I<br>
                &gt; still don't get a few things. I set up a gluster
                replica 2 volume like this:<br>
                &gt;<br>
                &gt; [root@gluster-test-1 ~]# gluster vol info vol_rep<br>
                &gt; Volume Name: vol_rep<br>
                &gt; Type: Replicate<br>
                &gt; Volume ID: b77db06d-2686-46c7-951f-e43bde21d8ec<br>
                &gt; Status: Started<br>
                &gt; Number of Bricks: 1 x 2 = 2<br>
                &gt; Transport-type: tcp<br>
                &gt; Bricks:<br>
                &gt; Brick1: gluster-test-1:/ladrillos/l1/l<br>
                &gt; Brick2: gluster-test-2:/ladrillos/l1/l<br>
                &gt; Options Reconfigured:<br>
                &gt; performance.cache-min-file-size: 90MB<br>
                &gt; performance.cache-max-file-size: 256MB<br>
                &gt; performance.cache-refresh-timeout: 60<br>
                &gt; performance.cache-size: 256MB<br>
                &gt; [root@gluster-test-1 ~]#<br>
                &gt;<br>
                &gt; Then I mounted the volume with gluster client on
                another machine. I created<br>
                &gt; an 80Mbytes file called 80, and here you have the
                reading test:<br>
                &gt;<br>
                &gt; [root@gluster-client-1 gluster_vol]# dd
                if=/mnt/gluster_vol/80 of=/dev/null<br>
                &gt; bs=1M<br>
                &gt; 80+0 records in<br>
                &gt; 80+0 records out<br>
                &gt; 83886080 bytes (84 MB) copied, 1,34145 s, 62,5 MB/s<br>
                &gt; [root@gluster-client-1 gluster_vol]# dd
                if=/mnt/gluster_vol/80 of=/dev/null<br>
                &gt; bs=1M<br>
                &gt; 80+0 records in<br>
                &gt; 80+0 records out<br>
                &gt; 83886080 bytes (84 MB) copied, 0,0246918 s, 3,4
                GB/s<br>
                &gt; [root@gluster-client-1 gluster_vol]# dd
                if=/mnt/gluster_vol/80 of=/dev/null<br>
                &gt; bs=1M<br>
                &gt; 80+0 records in<br>
                &gt; 80+0 records out<br>
                &gt; 83886080 bytes (84 MB) copied, 0,0195678 s, 4,3
                GB/s<br>
                &gt; [root@gluster-client-1 gluster_vol]#<br>
                <br>
              </div>
            </div>
            You are seeing the effect of client side kernel caching.&nbsp; If
            you want to see the actual throughput for reads run:<br>
            <br>
            sync; echo 3 &gt; /proc/sys/vm/drop_caches; dd blah<br>
            <br>
            Kernel caching happens on both the client and server side,
            when I want to see uncached performance I drop caches on
            both clients and servers:<br>
            <br>
            run_drop_cache()<br>
            {<br>
            &nbsp; &nbsp; for host in $MASTERNODE $NODE $CLIENT<br>
            &nbsp; &nbsp; do<br>
            &nbsp; &nbsp; &nbsp; &nbsp; ssh -i /root/.ssh/my_id root@${host} echo "Dropping
            cache on $host"<br>
            &nbsp; &nbsp; &nbsp; &nbsp; ssh -i /root/.ssh/my_id root@${host} sync<br>
            &nbsp; &nbsp; &nbsp; &nbsp; ssh -i /root/.ssh/my_id root@${host} "echo 3 &gt;
            /proc/sys/vm/drop_caches"<br>
            &nbsp; &nbsp; done<br>
            }<br>
            <br>
            HTH!<br>
            <span class="HOEnZb"><font color="#888888"><br>
                -b<br>
              </font></span>
            <div class="im HOEnZb"><br>
              &gt; Cache is working flawlessly, (even though that 80
              Mbytes is smaller than the<br>
              &gt; min-file-size value, but I don't care about it right
              now) what I don't get<br>
              &gt; is where cache is being stored. Is it stored on the
              client side or on the<br>
              &gt; server side? According to documentation, the io-cache
              translator could be<br>
              &gt; loaded on both sides (client and server), how can I
              know where it is being<br>
              &gt; loeaded? It looks like as it was being stored locally
              because of the speed,<br>
              &gt; but I'd like to be sure.<br>
              &gt;<br>
              &gt; Thanks!<br>
              &gt;<br>
              &gt; --<br>
              &gt; Pavlik Salles Juan Jos&eacute;<br>
              &gt; Blog - <a moz-do-not-send="true"
                href="http://viviendolared.blogspot.com" target="_blank">http://viviendolared.blogspot.com</a><br>
              &gt;<br>
            </div>
            <div class="HOEnZb">
              <div class="h5">&gt;
                _______________________________________________<br>
                &gt; Gluster-users mailing list<br>
                &gt; <a moz-do-not-send="true"
                  href="mailto:Gluster-users@gluster.org">Gluster-users@gluster.org</a><br>
                &gt; <a moz-do-not-send="true"
                  href="http://supercolony.gluster.org/mailman/listinfo/gluster-users"
                  target="_blank">http://supercolony.gluster.org/mailman/listinfo/gluster-users</a><br>
              </div>
            </div>
          </blockquote>
        </div>
        <br>
        <br clear="all">
        <div><br>
        </div>
        -- <br>
        <div dir="ltr">Pavlik Salles Juan Jos&eacute;
          <div>Blog - <a moz-do-not-send="true"
              href="http://viviendolared.blogspot.com" target="_blank">http://viviendolared.blogspot.com</a></div>
        </div>
      </div>
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      <br>
      <pre wrap="">_______________________________________________
Gluster-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Gluster-users@gluster.org">Gluster-users@gluster.org</a>
<a class="moz-txt-link-freetext" href="http://supercolony.gluster.org/mailman/listinfo/gluster-users">http://supercolony.gluster.org/mailman/listinfo/gluster-users</a></pre>
    </blockquote>
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