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<div class="moz-cite-prefix">13.07.2016 09:16, Pranith Kumar
Karampuri пишет:<br>
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cite="mid:CAOgeEnbDkcE99C8qV+imxE92RGh-3_GPUNaBXoMXgJd-vPDHpg@mail.gmail.com"
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<div class="gmail_quote">On Wed, Jul 13, 2016 at 10:38 AM,
Dmitry Melekhov <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:dm@belkam.com"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:dm@belkam.com">dm@belkam.com</a></a>></span> wrote:<br>
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<div>13.07.2016 09:04, Pranith Kumar Karampuri пишет:<br>
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<div class="gmail_quote">On Wed, Jul 13, 2016
at 10:29 AM, Dmitry Melekhov <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:dm@belkam.com"
target="_blank">dm@belkam.com</a>></span>
wrote:<br>
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style="margin:0 0 0 .8ex;border-left:1px
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<div>13.07.2016 08:56, Pranith Kumar
Karampuri пишет:<br>
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<div class="gmail_quote">On
Wed, Jul 13, 2016 at 10:23
AM, Dmitry Melekhov <span
dir="ltr"><<a
moz-do-not-send="true"
href="mailto:dm@belkam.com"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:dm@belkam.com">dm@belkam.com</a></a>></span>
wrote:<br>
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<div>13.07.2016 08:46,
Pranith Kumar
Karampuri пишет:<br>
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class="gmail_extra"><br>
<div
class="gmail_quote">On
Wed, Jul 13,
2016 at 10:10
AM, Dmitry
Melekhov <span
dir="ltr"><<a
moz-do-not-send="true" href="mailto:dm@belkam.com" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:dm@belkam.com">dm@belkam.com</a></a>></span>
wrote:<br>
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<div>13.07.2016
08:36, Pranith
Kumar
Karampuri
пишет:<br>
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type="cite">
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class="gmail_extra"><br>
<div
class="gmail_quote">On
Wed, Jul 13,
2016 at 9:35
AM, Dmitry
Melekhov <span
dir="ltr"><<a
moz-do-not-send="true" href="mailto:dm@belkam.com" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:dm@belkam.com">dm@belkam.com</a></a>></span>
wrote:<br>
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0 0
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solid;padding-left:1ex">13.07.2016
01:52,
Anuradha Talur
пишет:<span><br>
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----- Original
Message -----<br>
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From: "Dmitry
Melekhov" <<a
moz-do-not-send="true" href="mailto:dm@belkam.com" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:dm@belkam.com">dm@belkam.com</a></a>><br>
To: "Pranith
Kumar
Karampuri"
<<a
moz-do-not-send="true"
href="mailto:pkarampu@redhat.com" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:pkarampu@redhat.com">pkarampu@redhat.com</a></a>><br>
Cc:
"gluster-users"
<<a
moz-do-not-send="true"
href="mailto:gluster-users@gluster.org" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:gluster-users@gluster.org">gluster-users@gluster.org</a></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>
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</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>
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<div>It
detects wrong
length.
Because
checksum won't
match anymore.<br>
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<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>
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<div>What
use-case you
are trying out
is leading to
changing
things
directly on
the brick?<br>
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</blockquote>
</span> I'm trying to
test gluster failure
tolerance and right now
I'm not happy with it...<br>
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<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>
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<br>
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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>
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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>
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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>
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<div class="gmail_extra"><br>
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</blockquote>
Sorry, I'm not agree. <br>
As you know if on access missed or wrong lenghted file from fuse
client it is restored (healed), i.e. gluster recognizes file is
wrong and heal it , so I do not see any reason to provide this such
function as self-healing.<br>
Thank you!<br>
<br>
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