<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jul 13, 2016 at 10:38 AM, Dmitry Melekhov <span dir="ltr"><<a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>13.07.2016 09:04, Pranith Kumar
Karampuri пишет:<br>
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<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Jul 13, 2016 at 10:29 AM,
Dmitry Melekhov <span dir="ltr"><<a href="mailto:dm@belkam.com" target="_blank"></a><a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>13.07.2016 08:56, Pranith Kumar Karampuri пишет:<br>
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<div>
<div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Jul 13, 2016
at 10:23 AM, Dmitry Melekhov <span dir="ltr"><<a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>13.07.2016 08:46, Pranith Kumar
Karampuri пишет:<br>
</div>
<span>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed,
Jul 13, 2016 at 10:10 AM,
Dmitry Melekhov <span dir="ltr"><<a href="mailto:dm@belkam.com" target="_blank"></a><a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>13.07.2016 08:36,
Pranith Kumar Karampuri
пишет:<br>
</div>
<span>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On
Wed, Jul 13,
2016 at 9:35 AM,
Dmitry Melekhov
<span dir="ltr"><<a href="mailto:dm@belkam.com" target="_blank"></a><a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">13.07.2016
01:52,
Anuradha Talur
пишет:<span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
----- Original
Message -----<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
From: "Dmitry
Melekhov" <<a href="mailto:dm@belkam.com" target="_blank"></a><a href="mailto:dm@belkam.com" target="_blank">dm@belkam.com</a>><br>
To: "Pranith
Kumar
Karampuri"
<<a href="mailto:pkarampu@redhat.com" target="_blank"></a><a href="mailto:pkarampu@redhat.com" target="_blank">pkarampu@redhat.com</a>><br>
Cc:
"gluster-users"
<<a href="mailto:gluster-users@gluster.org" target="_blank"></a><a href="mailto:gluster-users@gluster.org" target="_blank">gluster-users@gluster.org</a>><br>
Sent: Tuesday,
July 12, 2016
9:27:17 PM<br>
Subject: Re:
[Gluster-users]
3.7.13, index
healing
broken?<br>
<br>
<br>
<br>
12.07.2016
17:39, Pranith
Kumar
Karampuri
пишет:<br>
<br>
<br>
<br>
Wow, what are
the steps to
recreate the
problem?<br>
<br>
just set file
length to
zero, always
reproducible.<br>
<br>
</blockquote>
If you are
setting the
file length to
0 on one of
the bricks
(looks like<br>
that is the
case), it is
not a bug.<br>
<br>
Index heal
relies on
failures seen
from the mount
point(s)<br>
to identify
the files that
need heal. It
won't be able
to recognize
any file<br>
modification
done directly
on bricks.
Same goes for
heal info
command which<br>
is the reason
heal info also
shows 0
entries.<br>
</blockquote>
<br>
</span> Well,
this makes
self-heal
useless then-
if any file is
accidently
corrupted or
deleted (yes!
if file is
deleted
directly from
brick this is
no recognized
by idex heal
too), then it
will not be
self-healed,
because
self-heal uses
index heal.<span><br>
</span></blockquote>
<div><br>
</div>
<div>It is
better to look
into bit-rot
feature if you
want to guard
against these
kinds of
problems.<br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</span> Bit rot detects
bit problems, not missing
files or their wrong
length, i.e. this is
overhead for such simple
task.<br>
</div>
</blockquote>
<div><br>
</div>
<div>It detects wrong length.
Because checksum won't match
anymore.<br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</span> Yes, sure. I guess that it will
detect missed files too. But it needs
far more resources, then just comparing
directories in bricks?<span><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div><br>
</div>
<div>What use-case you are
trying out is leading to
changing things directly on
the brick?<br>
</div>
</div>
</div>
</div>
</blockquote>
</span> I'm trying to test gluster
failure tolerance and right now I'm not
happy with it...<br>
</div>
</blockquote>
<div><br>
</div>
<div>Which cases of fault tolerance are you
not happy with? Making changes directly on
the brick or anything else as well?<br>
</div>
<br>
</div>
</div>
</div>
</blockquote>
</div>
</div>
I'll repeat:<span><br>
As I already said- if I for some reason ( real case
can be only by accident ) will delete file this will
not be detected by self-heal daemon, and, thus, will
lead to lower replication level, i.e. lower failure
tolerance. <br>
</span></div>
</blockquote>
<div><br>
To prevent such accidents you need to set selinux policies
so that files under the brick are not modified by accident
by any user. At least that is the solution I remember when
this was discussed 3-4 years back.<br>
</div>
</div>
<br>
</div>
</div>
</blockquote></div></div>
So only supported platfrom is linux? Or, may be, it is better to
improve self-healing to detect missing or wrong length files, I
guess this is very low cost in terms of host resources operation.<br>
Just a suggestion, may be we need to look to alternatives in near
future....<br>
<br>
</div>
</blockquote></div>This is a corner case, from design perspective it is generally not a good idea to optimize for the corner case. It is better to protect ourselves from the corner case (SElinux etc) or you can also use snapshots to protect against these kind of mishaps.<br></div><div class="gmail_extra"><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Pranith<br></div></div>
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