<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">The underlying device in this context is the NSD, network storage device. This has relation at all to 512 byte or 4K disk blocks. Usually around a meg, always a power of two. <br><br><div id="AppleMailSignature" dir="ltr"> -- ddj<div>Dave Johnson</div></div><div dir="ltr"><br>On Mar 21, 2019, at 9:22 AM, Dorigo Alvise (PSI) <<a href="mailto:alvise.dorigo@psi.ch">alvise.dorigo@psi.ch</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr">
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<div>Hi,</div>
<div>I'm a little bit puzzled about different meanings of blocksize for different GPFS installation (standard and gnr).</div>
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<div>From this page <a href="https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General%20Parallel%20File%20System%20(GPFS)/page/File%20System%20Planning" target="_blank">
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General%20Parallel%20File%20System%20(GPFS)/page/File%20System%20Planning</a></div>
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<div>I read:</div>
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<li><span style="font-size:12px"><span style="font-family:'arial' , 'helvetica' , sans-serif">The<span class="Apple-converted-space">
</span><b>blocksize</b><span class="Apple-converted-space"> </span>is the largest size IO that GPFS can issue to the underlying device</span></span></li><li><span style="font-size:12px"><span style="font-family:'arial' , 'helvetica' , sans-serif">A<span class="Apple-converted-space">
</span><b>subblock</b><span class="Apple-converted-space"> </span>is 1/32nd of blocksize. This is the smallest allocation to a single file</span></span></li></ul>
For non-gnr GPFS device is quite clear to me (I hope): it is a single spinning disk (or ssd). And I verified this on a small cluster composed of nsd using their local hard drive.<br>
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<div>Can someone explain what is the "device" in the case of GNR ? a single pdisk ?</div>
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<div>Thanks,</div>
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<div> Alvise<br>
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</div></blockquote><blockquote type="cite"><div dir="ltr"><span>_______________________________________________</span><br><span>gpfsug-discuss mailing list</span><br><span>gpfsug-discuss at <a href="http://spectrumscale.org">spectrumscale.org</a></span><br><span><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></span><br></div></blockquote></body></html>