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<div class="moz-cite-prefix">On 08/28/2013 06:34 AM, spameden wrote:<br>
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<div class="gmail_quote">2013/8/28 Kir Kolyshkin <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:kir@openvz.org" target="_blank">kir@openvz.org</a>></span><br>
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<div>On 08/27/2013 08:20 AM, spameden wrote:<br>
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<div>ArchLinux wiki says:<br>
<b>Warning: </b>Users need to be certain that
kernel version 2.6.33 or above is being used AND
that their SSD supports TRIM before attempting
to mount a partition with the <code
style="display:inline-block;padding:0.1em
0.3em">discard</code> flag. Data loss can
occur otherwise!<br>
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So I guess it's not in the OpenVZ kernel?<br>
<br>
I'd like to use TRIM because it increases
performance to SSD drastically!<br>
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You'd better check it with Red Hat, looking into their
RHEL6 documentation.<br>
<br>
My quick googling for "rhel6 kernel ssd discard" shows
that rhel6 kernel<br>
do support trim, they have backported it (as well as
tons of other stuff,<br>
so this is hardly 2.6.32 kernel anymore).<br>
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<div>I've just tested via hdparm (ofc it's not a perfect
tool to test out disk performance but still), here is what
I get on the latest 2.6.32-042stab079.5:<br>
<br>
# hdparm -t /dev/mapper/vg-root<br>
/dev/mapper/vg-root:<br>
Timing buffered disk reads: 828 MB in 3.00 seconds =
275.56 MB/sec<br>
<br>
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<div>on standard debian-7 kernel (3.2.0-4-amd64):<br>
# hdparm -t /dev/mapper/vg-root<br>
/dev/mapper/vg-root:<br>
Timing buffered disk reads: 1144 MB in 3.00 seconds =
381.15 MB/sec<br>
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<div>and it's only read speed test.<br>
<br>
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<div>I don't get why it differs so much?<br>
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My suggestion is, since this functionality is not directly related
to OpenVZ, and<br>
we usually don't change anything in this code (unless there is a
reason to), to<br>
try reproducing it on a stock RHEL6 kernel and, if it is
reproducible, file a bug<br>
to red hat or, if it's not reproducible, file a bug to openvz.<br>
<br>
Kir.<br>
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