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<div>Hi Marc,<br>
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<div>"Indirect block size" is well explained in this presentation: <br>
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<div><a href="http://files.gpfsug.org/presentations/2016/south-bank/D2_P2_A_spectrum_scale_metadata_dark_V2a.pdf" target="_blank">http://files.gpfsug.org/presentations/2016/south-bank/D2_P2_A_spectrum_scale_metadata_dark_V2a.pdf</a></div>
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<div>pages 37-41<br>
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<div>Cheers,</div>
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<div> Alvise<br>
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<div id="divRpF933280" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>From:</b> gpfsug-discuss-bounces@spectrumscale.org [gpfsug-discuss-bounces@spectrumscale.org] on behalf of Caubet Serrabou Marc (PSI) [marc.caubet@psi.ch]<br>
<b>Sent:</b> Tuesday, March 26, 2019 4:39 PM<br>
<b>To:</b> gpfsug main discussion list<br>
<b>Subject:</b> [gpfsug-discuss] GPFS v5: Blocksizes and subblocks<br>
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<div>Hi all,</div>
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<div>according to several GPFS presentations as well as according to the man pages:</div>
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<div><font face="Courier New"> Table 1. Block sizes and subblock sizes<br>
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+-------------------------------+-------------------------------+<br>
| Block size | Subblock size |<br>
+-------------------------------+-------------------------------+<br>
| 64 KiB | 2 KiB |<br>
+-------------------------------+-------------------------------+<br>
| 128 KiB | 4 KiB |<br>
+-------------------------------+-------------------------------+<br>
| 256 KiB, 512 KiB, 1 MiB, 2 | 8 KiB |<br>
| MiB, 4 MiB | |<br>
+-------------------------------+-------------------------------+<br>
| 8 MiB, 16 MiB | 16 KiB |<br>
+-------------------------------+-------------------------------+</font><br>
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<div>A block size of 8MiB or 16MiB should contain subblocks of 16KiB.</div>
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<div>However, when creating a new filesystem with 16MiB blocksize, looks like is using 128KiB subblocks:</div>
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<div><font face="Courier New">[root@merlindssio01 ~]# mmlsfs merlin<br>
flag value description<br>
------------------- ------------------------ -----------------------------------<br>
-f 8192 Minimum fragment (subblock) size in bytes (system pool)<br>
131072 Minimum fragment (subblock) size in bytes (other pools)<br>
-i 4096 Inode size in bytes<br>
-I 32768 Indirect block size in bytes<br>
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<div><font face="Courier New"> -n 128 Estimated number of nodes that will mount file system<br>
-B 1048576 Block size (system pool)<br>
16777216 Block size (other pools)<br>
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<div>What am I missing? According to documentation, I expect this to be a fixed value, or it isn't at all?<br>
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<div>On the other hand, I don't really understand the concept 'Indirect block size in bytes', can somebody clarify or provide some details about this setting?</div>
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<div>Thanks a lot and best regards,</div>
<div>Marc <br>
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<div class="PlainText">_________________________________________<br>
Paul Scherrer Institut <br>
High Performance Computing<br>
Marc Caubet Serrabou<br>
Building/Room: WHGA/019A</div>
<div class="PlainText"><font size="2"><span style="font-size:10pt">Forschungsstrasse, 111</span></font></div>
<div class="PlainText">5232 Villigen PSI<br>
Switzerland<br>
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Telephone: +41 56 310 46 67<br>
E-Mail: marc.caubet@psi.ch</div>
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