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<p style="margin-top:0;margin-bottom:0">So I found this: <a href="http://wiki.lustre.org/Handling_Full_OSTs" class="OWAAutoLink" id="LPlnk558116" previewremoved="true">http://wiki.lustre.org/Handling_Full_OSTs</a> which is what I thought I had followed before
but ran into hang issues. I did some quick testing with this and found that:</p>
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</p>
<p style="margin-top:0;margin-bottom:0">1. if I deactivate the OST in the MDS, no new files appear to be created on that OST (expected behavior) and no hangs.</p>
<p style="margin-top:0;margin-bottom:0">2. If I first create a file on the OST with it activated, then deactivate the OST, and OVERWRITE a file what was spanned on that OST, the indexes stay the same and the file successfully overwrites (the file spanned 4
OSTs, so perhaps a little more testing with a single OST in the index is necessary) </p>
<p style="margin-top:0;margin-bottom:0">3. Deactivating the OST shows it as inactive in the MDS but UP in the Client. (not expected.)</p>
<p style="margin-top:0;margin-bottom:0">4. I am able to delete a file that spans that OST with the OST deactivated, no hang.</p>
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I think the only thing here that concerns me a bit is #2.<br>
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<font face="Calibri,sans-serif" size="2"><span style="font-size:11pt">Jason Williams</span></font></div>
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<font face="Calibri,sans-serif" size="2"><span style="font-size:11pt">Systems and Data Center Operations.<br>
Maryland Advanced Research Computing Center (MARCC)<br>
Johns Hopkins University</span></font></div>
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<font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><a href="mailto:jasonw@jhu.edu" target="_blank" rel="noopener noreferrer" id="LPNoLP"><font color="#0563C1">jasonw@jhu.edu</font></a></span></font></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> lustre-discuss <lustre-discuss-bounces@lists.lustre.org> on behalf of Jason Williams <jasonw@jhu.edu><br>
<b>Sent:</b> Sunday, January 6, 2019 5:22:16 PM<br>
<b>To:</b> Mohr Jr, Richard Frank (Rick Mohr)<br>
<b>Cc:</b> lustre-discuss@lists.lustre.org<br>
<b>Subject:</b> Re: [lustre-discuss] Full OST, any way of avoiding it without hanging?</font>
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<div style="direction:ltr">Hi Rick, </div>
<div style="direction:ltr">I thought what I had done was disable it on the MDS, but perhaps I was following the wrong instructions. Do you know where the best instructions for what you are describing can be found? I would be willing to try again.</div>
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<div style="direction:ltr">—</div>
<div style="direction:ltr">Sent you tersely from my phone</div>
<div style="direction:ltr">Jason Williams</div>
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<div id="x_divRplyFwdMsg" dir="dir="ltr""><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Mohr Jr, Richard Frank (Rick Mohr) <rmohr@utk.edu><br>
<b>Sent:</b> Sunday, January 6, 2019 4:56 PM<br>
<b>To:</b> Jason Williams<br>
<b>Cc:</b> lustre-discuss@lists.lustre.org<br>
<b>Subject:</b> Re: [lustre-discuss] Full OST, any way of avoiding it without hanging?
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<br>
<br>
> On Jan 5, 2019, at 9:49 PM, Jason Williams <jasonw@jhu.edu> wrote:<br>
> <br>
> I have looked around the internet and found you can disable an OST, but when I have tried that, any writes (including deletes) to the OST hang the clients indefinitely. Does anyone know a way to make an OST basically "read-only" with the exception of deletes
so we can work to clear out the OST? <br>
<br>
What command did you use to disable the OST?<br>
<br>
There is a way to disable the OST on all the clients, but there is also a way to deactivate it on the MDS. The latter method should prevent the MDS from allocating any new files to the OST, but still allow clients to read and delete files on that OST.<br>
<br>
--<br>
Rick Mohr<br>
Senior HPC System Administrator<br>
National Institute for Computational Sciences<br>
http://www.nics.tennessee.edu<br>
<br>
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