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<div>Thank you, I've understood the math and the focus from free space to used one.</div>
<div><font size="2" face="sans-serif" color="blue"><font color="000000">The only thing the remain strange for me is that I've not seen something like this in other systems (IBM ESS GL2 and another Lenovo G240 and G260), but I guess that the reason could be
that they have much less used space, and allocated vdisks.</font></font></div>
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<div><font size="2" face="sans-serif" color="blue"><font color="000000"> thanks,</font></font></div>
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<div><font size="2" face="sans-serif" color="blue"><font color="000000"> Alvise</font><br>
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<div id="divRpF445690" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>From:</b> Sandeep Naik1 [sannaik2@in.ibm.com]<br>
<b>Sent:</b> Tuesday, February 12, 2019 8:50 PM<br>
<b>To:</b> gpfsug main discussion list; Dorigo Alvise (PSI)<br>
<b>Subject:</b> Re: [gpfsug-discuss] Unbalanced pdisk free space<br>
</font><br>
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<div><font size="2" face="sans-serif">Hi Alvise,</font><br>
<br>
<font size="2" face="sans-serif">Here is response to your question in </font><font size="2" face="sans-serif" color="blue">blue.</font><br>
<br>
<font size="2" face="sans-serif">Q - Can anybody tell me if it is normal that all the pdisks of both my recovery groups, residing on the same physical enclosure have free space equal to (more or less) 1/3 of the free space of the pdisks residing on the other
physical enclosure (see attached text files for the command line output) ?</font><br>
<font size="2" face="sans-serif"><br>
</font><font size="2" face="sans-serif" color="blue">Yes it is normal to see variation in free space between pdisks. The variation should be seen in the context of used space and not free space. GNR try to balance space equally across enclosures (failure groups).
One enclosure has one SSD (per RG) so it has 41 disk in DA1 while the other one has 42. Enclosure with 42 disk show 360 GiB free space while one with 41 disk show 120 GiB. If you look at used capacity and distribute it equally between two enclosures you will
notice that used capacity is almost same between two enclosure.</font><br>
<br>
<font size="2" face="sans-serif" color="blue">42 * (10240 - 360) ≃ 41 * (10240 - 120)</font><br>
<font size="2" face="sans-serif"> </font><font size="2" face="sans-serif" color="blue"><br>
</font><font size="2" face="sans-serif">I guess when the least free disks are fully occupied (while the others are still partially free) write performance will drop by a factor of two. Correct ?
<br>
Is there a way (considering that the system is in production) to fix (rebalance) this free space among all pdisk of both enclosures ?</font><br>
<br>
<font size="2" face="sans-serif" color="blue">You should see in context of size of pdisk, which in your case in 10TB. The disk showing 120GB free is 98% full while the one showing 360GB free is 96% full. This free space is available for creating vdisks and
should not be confused with free space available in filesystem. Your pdisk are by and large equally filled so there will be no impact on write performance because of small variation in free space.
</font><br>
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<font size="2" face="sans-serif" color="blue">Hope this helps</font><br>
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<font size="2" face="sans-serif" color="blue">Thanks,<br>
<br>
Sandeep Naik<br>
Elastic Storage server / GPFS Test <br>
ETZ-B, Hinjewadi Pune India<br>
(+91) 8600994314</font><br>
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<font size="1" face="sans-serif" color="#5f5f5f">From: </font><font size="1" face="sans-serif">"Dorigo Alvise (PSI)" <alvise.dorigo@psi.ch></font><br>
<font size="1" face="sans-serif" color="#5f5f5f">To: </font><font size="1" face="sans-serif">gpfsug main discussion list <gpfsug-discuss@spectrumscale.org></font><br>
<font size="1" face="sans-serif" color="#5f5f5f">Date: </font><font size="1" face="sans-serif">31/01/2019 04:07 PM</font><br>
<font size="1" face="sans-serif" color="#5f5f5f">Subject: </font><font size="1" face="sans-serif">Re: [gpfsug-discuss] Unbalanced pdisk free space</font><br>
<font size="1" face="sans-serif" color="#5f5f5f">Sent by: </font><font size="1" face="sans-serif">gpfsug-discuss-bounces@spectrumscale.org</font><br>
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<font size="2" face="Tahoma">They're attached.</font><br>
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<font size="2" face="Tahoma">Thanks!</font><br>
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<font size="2" face="Tahoma"> Alvise</font><br>
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<font size="2" face="Tahoma"><b>From:</b> gpfsug-discuss-bounces@spectrumscale.org [gpfsug-discuss-bounces@spectrumscale.org] on behalf of IBM Spectrum Scale [scale@us.ibm.com]<b><br>
Sent:</b> Wednesday, January 30, 2019 9:25 PM<b><br>
To:</b> gpfsug main discussion list<b><br>
Subject:</b> Re: [gpfsug-discuss] Unbalanced pdisk free space</font><font size="3"><br>
</font><br>
<font size="2" face="sans-serif">Alvise,</font><font size="3"><br>
</font><font size="2" face="sans-serif"><br>
Could you send us the output of the following commands from both server nodes.</font><font size="3">
</font>
<ul>
<li><font size="2" face="sans-serif">mmfsadm dump nspdclient > /tmp/dump_nspdclient.<nodeName> </font></li><li><font size="2" face="sans-serif">mmfsadm dump pdisk > /tmp/dump_pdisk.<nodeName></font></li></ul>
<font size="2" face="sans-serif">Regards, The Spectrum Scale (GPFS) team<br>
<br>
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If you feel that your question can benefit other users of Spectrum Scale (GPFS), then please post it to the public IBM developerWroks Forum at
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The forum is informally monitored as time permits and should not be used for priority messages to the Spectrum Scale (GPFS) team.</font><font size="3"><br>
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From: </font><font size="1" face="sans-serif">"Dorigo Alvise (PSI)" <alvise.dorigo@psi.ch></font><font size="1" face="sans-serif" color="#5f5f5f"><br>
To: </font><font size="1" face="sans-serif">"gpfsug-discuss@spectrumscale.org" <gpfsug-discuss@spectrumscale.org></font><font size="1" face="sans-serif" color="#5f5f5f"><br>
Date: </font><font size="1" face="sans-serif">01/30/2019 08:24 AM</font><font size="1" face="sans-serif" color="#5f5f5f"><br>
Subject: </font><font size="1" face="sans-serif">[gpfsug-discuss] Unbalanced pdisk free space</font><font size="1" face="sans-serif" color="#5f5f5f"><br>
Sent by: </font><font size="1" face="sans-serif">gpfsug-discuss-bounces@spectrumscale.org</font><font size="3"><br>
</font>
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Hello,<br>
I've a Lenovo Spectrum Scale system DSS-G220 (software dss-g-2.0a) composed of<br>
2x x3560 M5 IO server nodes<br>
1x x3550 M5 client/support node<br>
2x disk enclosures D3284<br>
GPFS/GNR 4.2.3-7</font><font size="3"><br>
</font><font size="2" face="Tahoma"><br>
Can anybody tell me if it is normal that all the pdisks of both my recovery groups, residing on the same physical enclosure have free space equal to (more or less) 1/3 of the free space of the pdisks residing on the other physical enclosure (see attached text
files for the command line output) ?</font><font size="3"><br>
</font><font size="2" face="Tahoma"><br>
I guess when the least free disks are fully occupied (while the others are still partially free) write performance will drop by a factor of two. Correct ?
<br>
Is there a way (considering that the system is in production) to fix (rebalance) this free space among all pdisk of both enclosures ?</font><font size="3"><br>
</font><font size="2" face="Tahoma"><br>
Should I open a PMR to IBM ?</font><font size="3"><br>
</font><font size="2" face="Tahoma"><br>
Many thanks,</font><font size="3"><br>
</font><font size="2" face="Tahoma"><br>
Alvise</font><font size="3"><br>
</font><font size="1" face="sans-serif"><br>
[attachment "rg1" deleted by Brian Herr/Poughkeepsie/IBM] [attachment "rg2" deleted by Brian Herr/Poughkeepsie/IBM]
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[attachment "dump_nspdclient.sf-dssio-1" deleted by Sandeep Naik1/India/IBM] [attachment "dump_nspdclient.sf-dssio-2" deleted by Sandeep Naik1/India/IBM] [attachment "dump_pdisk.sf-dssio-1" deleted by Sandeep Naik1/India/IBM] [attachment "dump_pdisk.sf-dssio-2"
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