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<p class="MsoNormal"><span lang="EN-US">>> there is a certain risk of data not reaching the hard disk soundly.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">>It seems so but what is a way to catch the reason?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">If you use LVM, did you set the correct filter in lvm.conf?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Edit <o:p></o:p></span></p>
<p class="MsoNormal"><i><span lang="EN-US" style="color:#1F497D">/etc/lvm/lvm.conf<o:p></o:p></span></i></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">And allow only “drbd” devices to be used for LVM<o:p></o:p></span></p>
<div style="border:solid windowtext 1.0pt;padding:1.0pt 4.0pt 1.0pt 4.0pt">
<p class="MsoNormal" style="background:#F2F2F2"><span lang="EN-US" style="font-size:10.0pt;font-family:"Courier New";color:#1F497D"> filter = [ "a|drbd|", "r|.*|" ]<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span lang="EN-US" style="color:#1F497D">Turn off LVM cache</span><span lang="EN-US" style="font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<div style="border:solid windowtext 1.0pt;padding:0cm 4.0pt 1.0pt 4.0pt">
<p class="MsoNormal" style="background:#F2F2F2"><span lang="EN-US" style="font-size:10.0pt;font-family:Courier;color:#1F497D">write_cache_state = 0<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Do you use some custom disk caching module like flashcache?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">I have had data integrity issues when I used flashcache with drbd.<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">>> - not use dual-primary<br>
>I can't because I need online migration (I know it's dangerous to do migration now, because data can be not synced properly)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">To avoid the dual primary mode I have put all storage on an a HA iSCSI SAN, then drbd can be used in primary/secondary mode. If you want I can
send you my setup notes using centos 6.4 drbd, tgt and pacemaker.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Maurits van de Lande<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Van:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:drbd-user-bounces@lists.linbit.com">drbd-user-bounces@lists.linbit.com</a> [<a href="mailto:drbd-user-bounces@lists.linbit.com">mailto:drbd-user-bounces@lists.linbit.com</a>]
<b>Namens </b>Stanislav German-Evtushenko<br>
<b>Verzonden:</b> maandag 25 maart 2013 10:43<br>
<b>Aan:</b> Felix Frank<br>
<b>CC:</b> <a href="mailto:drbd-user@lists.linbit.com">drbd-user@lists.linbit.com</a><br>
<b>Onderwerp:</b> Re: [DRBD-user] Uncatchable DRBD out-of-sync issue<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi,<br>
<br>
> there is a certain risk of data not reaching the hard disk soundly.<o:p></o:p></p>
</div>
<p class="MsoNormal">It seems so but what is a way to catch the reason?<o:p></o:p></p>
<div>
<p class="MsoNormal"><br>
> What's your hard disk stack?<o:p></o:p></p>
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<p class="MsoNormal">RAID 1+0 on both nodes.<o:p></o:p></p>
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<p class="MsoNormal"><br>
> If you have the freedom, there are some things to try, e.g.<br>
> - not use ethernet bonding<o:p></o:p></p>
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<p class="MsoNormal">I can try but it will decrease bandwidth from 200MiB/s to 100MiB/s and disable redundancy.<br>
> - not use dual-primary<br>
I can't because I need online migration (I know it's dangerous to do migration now, because data can be not synced properly)<o:p></o:p></p>
<div>
<p class="MsoNormal"><br>
> - use a smaller partition<o:p></o:p></p>
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<p class="MsoNormal">Why?<br>
<br>
Best regards,<br>
Stanislav <o:p></o:p></p>
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