<html><body><p><font size="2">Folks,</font><br><br><font size="2">Also quoting a previous post:</font><br>
<ul><ul><ul>Thanks Mark, <br><br>I did not know, we could explicitly mention sub-block size when creating File system. It is no-where mentioned in the “man mmcrfs”. <br>Is this a new GPFS 5.0 feature?<br><br>Also, i see from the “man mmcrfs” that the default sub-block size for 8M and 16M is 16K.</ul></ul></ul><br><br><font size="2">Specifying the number of subblocks per block or the subblock size in mmcrfs is not currently supported. The subblock size is automatically chosen based on the block size, as described in 'Table 1. Block sizes and subblock sizes' in 'man mmcrfs'.</font><br><br><font size="2"> Felipe</font><br><br><font size="2">----<br>Felipe Knop knop@us.ibm.com<br>GPFS Development and Security<br>IBM Systems<br>IBM Building 008<br>2455 South Rd, Poughkeepsie, NY 12601<br>(845) 433-9314 T/L 293-9314<br><br></font><br><br><img width="16" height="16" src="cid:1__=8FBB08F0DF82FE4A8f9e8a93df938690918c8FB@" border="0" alt="Inactive hide details for "Marc A Kaplan" ---03/30/2018 02:48:02 PM---Look at my example, again, closely. I chose the blocksiz"><font size="2" color="#424282">"Marc A Kaplan" ---03/30/2018 02:48:02 PM---Look at my example, again, closely. I chose the blocksize as 16M and subblock size as 4K and the i</font><br><br><font size="2" color="#5F5F5F">From: </font><font size="2">"Marc A Kaplan" <makaplan@us.ibm.com></font><br><font size="2" color="#5F5F5F">To: </font><font size="2">gpfsug main discussion list <gpfsug-discuss@spectrumscale.org></font><br><font size="2" color="#5F5F5F">Date: </font><font size="2">03/30/2018 02:48 PM</font><br><font size="2" color="#5F5F5F">Subject: </font><font size="2">Re: [gpfsug-discuss] sublocks per block in GPFS 5.0</font><br><font size="2" color="#5F5F5F">Sent by: </font><font size="2">gpfsug-discuss-bounces@spectrumscale.org</font><br><hr width="100%" size="2" align="left" noshade style="color:#8091A5; "><br><br><br><font size="2">Look at my example, again, closely. I chose the blocksize as 16M and subblock size as 4K and the inodesize as 1K.... <br>Developer works is a good resource, but articles you read there may be incomplete or contain mistakes.</font><br><font size="2"><br>The official IBM Spectrum Scale cmd and admin guide documents, are "trustworthy" but may not be perfect in all respects. "Trust but Verify" and YMMV. ;-)<br><br>As for why/how to choose "good sizes", that depends what objectives you want to achieve, and "optimal" may depend on what hardware you are running.<br>Run your own trials and/or ask performance experts. There are usually "tradeoffs" and OTOH when you get down to it, some choices may not be all-that-important in actual deployment and usage. That's why we have defaults values - try those first and leave the details and tweaking aside until you have good reason ;-)</font><tt><font size="2">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></font></tt><tt><font size="2"><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=oNT2koCZX0xmWlSlLblR9Q&m=6_33HG_HPw9JkUKuyY_SrveiPQ_bnA4JHZ0F7l01ohc&s=HLsts8ySRm-SVYLUNhCt2SxsoP3Ph02ehKmGnqpXbPc&e=">https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=oNT2koCZX0xmWlSlLblR9Q&m=6_33HG_HPw9JkUKuyY_SrveiPQ_bnA4JHZ0F7l01ohc&s=HLsts8ySRm-SVYLUNhCt2SxsoP3Ph02ehKmGnqpXbPc&e=</a></font></tt><tt><font size="2"><br></font></tt><br><br><BR>
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