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<div class="moz-cite-prefix">On 02/06/2016 12:19 AM, Simon
Turcotte-Langevin wrote:<br>
</div>
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cite="mid:b1c32219131a4ba4ad03082faa5fdd1f@MSR-MAIL-EXCH01.ubisoft.org"
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<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Good
day to you Pranith,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Thank
you for your answer, it was exactly this. However, we still
have an issue with RELATIME on GlusterFS.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Stating
the file does not modify atime anymore, with quick-read
disabled, however cat-ing the file does not replicate the
atime.</span></p>
</div>
</blockquote>
This is because of open-behind feature. Disable open-behind with:
"gluster volume set <volname> open-behind off". I believe you
will see the atime behavior you want to see with it. This will
reduce the performance of small file reads (< 64KB). Instead of
one lookup over the network now it will do, lookup + open(This will
be sent to both the replica bricks which updates atime) + read (Only
one of the bricks). Let me know if you want any more information.<br>
<br>
Pranith<br>
<br>
<blockquote
cite="mid:b1c32219131a4ba4ad03082faa5fdd1f@MSR-MAIL-EXCH01.ubisoft.org"
type="cite">
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">If
I touch manually the file, the atime (or utimes) is
replicated correctly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">So
to sum it up:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l1 level1 lfo5"><!--[if !supportLists]--><span
style="font-family:Symbol;color:#1F497D" lang="EN-US"><span
style="mso-list:Ignore">·<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span
style="color:#1F497D" lang="EN-US">[node1] Touch –a file1
<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l1
level2 lfo5">
<!--[if !supportLists]--><span
style="font-family:"Courier New";color:#1F497D"
lang="EN-US"><span style="mso-list:Ignore">o<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-family:Wingdings;color:#1F497D" lang="EN-US">à</span><span
style="color:#1F497D" lang="EN-US"> Access time is right on
[node1] [node2] and [node3]<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l1 level1 lfo5"><!--[if !supportLists]--><span
style="font-family:Symbol;color:#1F497D" lang="EN-US"><span
style="mso-list:Ignore">·<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span
style="color:#1F497D" lang="EN-US">[node1] Cat file1
<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l1
level2 lfo5">
<!--[if !supportLists]--><span
style="font-family:"Courier New";color:#1F497D"
lang="EN-US"><span style="mso-list:Ignore">o<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-family:Wingdings;color:#1F497D" lang="EN-US">à</span><span
style="color:#1F497D" lang="EN-US"> Access time is right on
[node1]<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l1
level2 lfo5">
<!--[if !supportLists]--><span
style="font-family:"Courier New";color:#1F497D"
lang="EN-US"><span style="mso-list:Ignore">o<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-family:Wingdings;color:#1F497D" lang="EN-US">à</span><span
style="color:#1F497D" lang="EN-US"> Access time is wrong on
[node2] and [node3]<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Would
you have any idea what is going on behind the curtain, and
if there is any way to fix that behavior?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Thank
you,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="color:windowtext;mso-fareast-language:FR-CA"
lang="EN-US">From:</span></b><span
style="color:windowtext;mso-fareast-language:FR-CA"
lang="EN-US"> Pranith Kumar Karampuri
[<a class="moz-txt-link-freetext" href="mailto:pkarampu@redhat.com">mailto:pkarampu@redhat.com</a>]
<br>
<b>Sent:</b> 5 février 2016 00:55<br>
<b>To:</b> Simon Turcotte-Langevin
<a class="moz-txt-link-rfc2396E" href="mailto:simon.turcotte-langevin@ubisoft.com"><simon.turcotte-langevin@ubisoft.com></a>;
<a class="moz-txt-link-abbreviated" href="mailto:gluster-users@gluster.org">gluster-users@gluster.org</a><br>
<b>Cc:</b> UPS_Development
<a class="moz-txt-link-rfc2396E" href="mailto:UPS_Development@ubisoft.com"><UPS_Development@ubisoft.com></a><br>
<b>Subject:</b> Re: [Gluster-users] GlusterFS behaviour
on stat syscall with relatime activated<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span
style="font-size:12.0pt;mso-fareast-language:FR-CA"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal">On 02/03/2016 10:12 PM, Simon
Turcotte-Langevin wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span lang="EN-US">Hi, we have multiple
clusters of GlusterFS which are mostly alike. The typical
setup is as such:</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Cluster of
3 nodes</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Replication
factor of 3</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Each node
has 1 brick, mounted on XFS with RELATIME and NODIRATIME</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Each node
has 8 disks in RAID 0 hardware</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">The main problem we
are facing is that observation of the access time of a
file on the volume will update the access time.</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">The steps to reproduce
the problem are:</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo4"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Create a
file (echo ‘some data’ > /mnt/gv0/file)</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo4"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Touch its
mtime and atime to some past date (touch –d 19700101
/mnt/gv0/file)</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo4"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Touch its
mtime to the current timestamp (touch –m /mnt/gv0/file)</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo4"><!--[if !supportLists]--><span
style="mso-list:Ignore">-<span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]--><span lang="EN-US">Stat the
file until atime is updated (stat /mnt/gv0/file)</span><o:p></o:p></p>
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l2
level2 lfo4">
<!--[if !supportLists]--><span
style="font-family:"Courier New""><span
style="mso-list:Ignore">o<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Sometimes
it’s instant, sometimes it requires to execute the above
command a couple of time</span><o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif;mso-fareast-language:FR-CA">atime changes
on open call.<br>
<br>
Quick-read xlator opens the file and reads the content on
'lookup' which gets triggered in stat. It does that to serve
reads from memory to reduce number of network round trips
for small files. Could you disable that xlator and try the
experiment? On my machine the time didn't change after I
disabled that feature using:<br>
<br>
"gluster volume set <volname> quick-read off"<br>
<br>
Pranith<br>
<br>
<o:p></o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoListParagraph"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">On the IRC channel, I spoke to a developer
(nickname ndevos) who said that it might be a getxattr()
syscall that could be called when stat() is called on a
replicated volume.</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">Anybody can reproduce this issue? Is it a
bug, or is it working as intended? Is there any
workaround?</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">Thank you,</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">Simon</span><o:p></o:p></p>
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style="font-size:12.0pt;font-family:"Times New
Roman",serif;mso-fareast-language:FR-CA"><br>
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<br>
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<pre>_______________________________________________<o:p></o:p></pre>
<pre>Gluster-users mailing list<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:Gluster-users@gluster.org">Gluster-users@gluster.org</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.gluster.org/mailman/listinfo/gluster-users">http://www.gluster.org/mailman/listinfo/gluster-users</a><o:p></o:p></pre>
</blockquote>
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style="font-size:12.0pt;font-family:"Times New
Roman",serif;mso-fareast-language:FR-CA"><o:p> </o:p></span></p>
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