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<div class="moz-cite-prefix">On 02/03/2016 10:12 PM, Simon
Turcotte-Langevin wrote:<br>
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<div class="WordSection1">
<p class="MsoNormal"><span lang="EN-US">Hi, we have multiple
clusters of GlusterFS which are mostly alike. The typical
setup is as such:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Cluster
of 3 nodes<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Replication
factor of 3<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Each
node has 1 brick, mounted on XFS with RELATIME and
NODIRATIME<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Each
node has 8 disks in RAID 0 hardware<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></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.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The steps to reproduce
the problem are:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo3"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Create
a file (echo ‘some data’ > /mnt/gv0/file)<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo3"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Touch
its mtime and atime to some past date (touch –d 19700101
/mnt/gv0/file)<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo3"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Touch
its mtime to the current timestamp (touch –m /mnt/gv0/file)<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l2 level1 lfo3"><!--[if !supportLists]--><span
lang="EN-US"><span style="mso-list:Ignore">-<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span lang="EN-US">Stat
the file until atime is updated (stat /mnt/gv0/file)<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l2
level2 lfo3">
<!--[if !supportLists]--><span
style="font-family:"Courier New"" lang="EN-US"><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></p>
</div>
</blockquote>
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>
<blockquote
cite="mid:89ee984d089a4bed825c4d9aaf1aae58@MSR-MAIL-EXCH01.ubisoft.org"
type="cite">
<div class="WordSection1">
<p class="MsoListParagraph"
style="margin-left:72.0pt;text-indent:-18.0pt;mso-list:l2
level2 lfo3"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US"><o:p> </o:p></span></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.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US"><o:p> </o:p></span></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?<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">Thank you,<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:0cm"><span
lang="EN-US">Simon<o:p></o:p></span></p>
</div>
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