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<font face="Arial">Hello Folks,</font><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><br>
<br>
</span></font><font face="Arial">we have one LUN on our MGS|MGT Server.<br>
The LUN is availible over two pathes.<br>
( Multipathing with OS embeded rdac driver, SLES11)<br>
<br>
</font>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">snowball-mds2:/proc/fs
# multipath -ll <o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">3600a0b80005a7215000002034b952b00
dm-10 SUN,LCSM100_S<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">[size=419G][features=1
queue_if_no_path][hwhandler=1
rdac][rw]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">\_
round-robin 0 [prio=6][active]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"> \_ 6:0:1:1
sdd 8:48 [active][ready]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">\_
round-robin 0 [prio=1][enabled]<o:p></o:p></span></font></p>
<font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"> \_ 6:0:0:1
sdb 8:16 [active][ghost]</span></font><font face="Arial"><br>
<br>
We create an LVM device on this LUN.<br>
<br>
</font>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">snowball-mds2:~
# lvscan<o:p></o:p></span></font></p>
<font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p></o:p></span></font><font
size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">
ACTIVE '/dev/mds2/mgs2' [418.68 GB]
inherit</span></font><font face="Arial"><br>
<br>
</font>
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<pre><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p></o:p></span></font><big><font
size="2" face="Arial"><big><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>everything works fine.</o:p></span></big></font></big></pre>
<pre><big><font size="2" face="Arial"><big><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p></o:p></span></big></font></big></pre>
<pre><big><font size="2" face="Arial"><big><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>Now we switched the controller on the storage to simulate a path failover:</o:p></span></big></font></big></pre>
<pre><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p></o:p></span></font></pre>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"># multipath
-ll<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">3600a0b80005a7215000002034b952b00
dm-10 SUN,LCSM100_S<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">[size=419G][features=1
queue_if_no_path][hwhandler=1
rdac][rw]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">\_
round-robin 0 [prio=1][enabled]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"> \_ 6:0:1:1
sdd 8:48 [active][ghost]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">\_
round-robin 0 [prio=6][enabled]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"> \_ 6:0:0:1
sdb 8:16 [active][ready]<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p> <br>
after that the MDT Device is unhealthy:<br>
<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">snowball-mds2:/proc/fs
# cat
/proc/fs/lustre/health_check<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">device
tools-MDT0000 reported unhealthy<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">NOT HEALTHY<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>and we
can not remount the filesystem -> the filesystem is not writeable</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>We can
see this in /var/log/messages, as there is a warning about this
filesystem beeing in read-only mode.<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p><br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">snowball-mds2:/proc/fs
# tunefs.lustre --dryrun
/dev/mds2/mgs2<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">checking for
existing Lustre data: found
CONFIGS/mountdata<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Reading
CONFIGS/mountdata<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"> Read
previous values:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Target:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Index:
unassigned<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Lustre FS:
lustre<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Mount type:
ldiskfs<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Flags:
0x70<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">
(needs_index first_time update )<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Persistent
mount opts:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Parameters:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p> <br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">tunefs.lustre
FATAL: must set target type:
MDT,OST,MGS<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">tunefs.lustre:
exiting with 22 (Invalid argument)<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p> <br>
<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>after a
reboot everything works fine again.<br>
Is there a problem this the lvm configuration?<br>
We found an document to enable multipathing on lvm2, but it doesent
work.</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>Is
lustre 1.8.2 supported on lvm and multipathing?<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p><br>
We are concerning about the availability and consistency about the
lustre filesystem e.g. metadata. Because<br>
the metadata isn't correctly acailable after a path failover of the
metadata-(MDT)-device. The path-failover should<br>
be absolutely transparent to the LVM LUN used for the MDT and the
Lustre-FS on it. Is this correct? <br>
We tested the path-failover functionality with a simple ext3-fs on the
device and we could not see any problem.<br>
Also I think it is not recommended to configure the lustre filesystem
to remain in write-mode when an "error" accours, isnt't it?<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p><br>
Does anyone have experiance with the above mentioned configuration? Are
there any known bugs?<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p><br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>Thanks
and regards<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>Matthias<br>
<br>
<br>
</o:p></span></font></p>
<font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p></o:p></span></font>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><o:p>Additional
Information:<br>
</o:p></span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">snowball-mds2:/proc/fs
# uname -a<o:p></o:p></span></font></p>
<font size="2" face="Arial"><span
style="font-size: 10pt; font-family: Arial;" lang="EN-GB">Linux
snowball-mds2
2.6.27.39-0.3_lustre.1.8.2-default #1 SMP 2009-11-23 12:57:38 +0100
x86_64
x86_64 x86_64 GNU/Linux</span></font><font face="Arial"><br>
</font></div>
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