<html><body><p><font size="2" face="sans-serif">Hi Stephen,</font><br><br><font size="2" face="sans-serif">Currently such a feature is not available in Spectrum Scale product.</font><br><br><br><font size="2" face="sans-serif">Regards, The Spectrum Scale (GPFS) team<br><br>------------------------------------------------------------------------------------------------------------------<br>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 <a href="https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000000479">https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000000479</a>. <br><br>If your query concerns a potential software error in Spectrum Scale (GPFS) and you have an IBM software maintenance contract please contact 1-800-237-5511 in the United States or your local IBM Service Center in other countries. <br><br>The forum is informally monitored as time permits and should not be used for priority messages to the Spectrum Scale (GPFS) team.</font><br><br><img width="16" height="16" src="cid:1__=0ABB02C8DFF667CA8f9e8a93df938690@ibm.com" border="0" alt="Inactive hide details for "Stephen Ulmer" ---02-06-2022 11.32.27 PM---This only adds a checksum to the NSD wire protocol. The q"><font size="2" color="#424282" face="sans-serif">"Stephen Ulmer" ---02-06-2022 11.32.27 PM---This only adds a checksum to the NSD wire protocol. The question was about detecting data corruption</font><br><br><font size="1" color="#5F5F5F" face="sans-serif">From: </font><font size="1" face="sans-serif">"Stephen Ulmer" <ulmer@ulmer.org></font><br><font size="1" color="#5F5F5F" face="sans-serif">To: </font><font size="1" face="sans-serif">"gpfsug main discussion list" <gpfsug-discuss@gpfsug.org></font><br><font size="1" color="#5F5F5F" face="sans-serif">Date: </font><font size="1" face="sans-serif">02-06-2022 11.32 PM</font><br><font size="1" color="#5F5F5F" face="sans-serif">Subject: </font><font size="1" face="sans-serif">[EXTERNAL] Re: [gpfsug-discuss] Protection against silent data corruption</font><br><font size="1" color="#5F5F5F" face="sans-serif">Sent by: </font><font size="1" face="sans-serif">"gpfsug-discuss" <gpfsug-discuss-bounces@gpfsug.org></font><br><hr width="100%" size="2" align="left" noshade style="color:#8091A5; "><br><br><br><font size="1" color="#FFFFFF" face="serif">This only adds a checksum to the NSD wire protocol. The question was about detecting data corruption at rest. -- Stephen On Jun 2, 2022, at 1:01 PM, Achim Rehor <Achim.Rehor@de.ibm.com> wrote: hi Stephan, </font><br><font size="1" color="#FFFFFF" face="serif">ZjQcmQRYFpfptBannerStart</font><br><font size="2" face="Arial"><b>This Message Is From an External Sender </b></font><br><font size="1" face="Arial">This message came from outside your organization. </font><br><font size="3" face="serif"> </font><br><font size="1" color="#FFFFFF" face="serif">ZjQcmQRYFpfptBannerEnd</font><br><font size="3" face="serif">This only adds a checksum to the NSD wire protocol. The question was about detecting data corruption at rest.</font><br><br><font size="3" face="serif">-- <br>Stephen<br><br></font><br>
<ul style="padding-left: 36pt; margin-left: 0px"><font size="3" face="serif">On Jun 2, 2022, at 1:01 PM, Achim Rehor <</font><a href="mailto:Achim.Rehor@de.ibm.com"><font size="3" color="#0000FF" face="serif"><u>Achim.Rehor@de.ibm.com</u></font></a><font size="3" face="serif">> wrote:</font><br><br><font size="3" face="serif">hi Stephan, </font><br><br><font size="3" face="serif">there is, see mmchconfig man page : <br></font><br><font size="3" face="serif">nsdCksumTraditional</font><br><font size="3" face="serif">This attribute enables checksum data-integrity checking between a traditional NSD client node and its NSD server. Valid values are yes and no. The default value is no.</font><br><font size="3" face="serif">(Traditional in this context means that the NSD client and server are configured with IBM Spectrum Scale rather than with IBM Spectrum Scale RAID. </font><br><font size="3" face="serif">The latter is a component of IBM Elastic Storage Server (ESS) and of IBM GPFS Storage Server (GSS).)</font><br><br><font size="3" face="serif">The checksum procedure detects any corruption by the network of the data in the NSD RPCs that are exchanged between the NSD client and the </font><br><font size="3" face="serif">server. A checksum error triggers a request to retransmit the message.</font><br><br><font size="3" face="serif">When this attribute is enabled on a client node, the client indicates in each of its requests to the server that it is using checksums. The server uses checksums only in</font><br><font size="3" face="serif">response to client requests in which the indicator is set. A client node that accesses a file system that belongs to another cluster can use checksums in the same way.</font><br><br><font size="3" face="serif">You can change the value of the this attribute for an entire cluster without shutting down the mmfsd daemon, or for one or more nodes without restarting the nodes.</font><br><br><font size="3" face="serif">Note:</font><br><font size="3" face="serif">* Enabling this feature can result in significant I/O performance degradation and a considerable increase in CPU usage.</font><br><br><font size="3" face="serif">* To enable checksums for a subset of the nodes in a cluster, issue a command like the following one:</font><br><font size="3" face="serif"> mmchconfig nsdCksumTraditional=yes -i -N <subset-of-nodes></font><br><br><font size="3" face="serif"> The -N flag is valid for this attribute.</font><br><br><tt><font size="3">-- </font></tt><br><font size="3" face="serif">Mit freundlichen Grüßen / Kind regards</font><br><br><font size="3" face="serif">Achim Rehor</font><br><br><font size="3" face="serif">Technical Support Specialist Spectrum Scale and ESS (SME)</font><br><font size="3" face="serif">Advisory Product Services Professional</font><br><font size="3" face="serif">IBM Systems Storage Support - EMEA</font><br><br><a href="mailto:Achim.Rehor@de.ibm.com"><font size="3" color="#0000FF" face="serif"><u>Achim.Rehor@de.ibm.com</u></font></a><font size="3" face="serif"> +49-170-4521194 </font><br><font size="3" face="serif">IBM Deutschland GmbH </font><br><font size="3" face="serif">Vorsitzender des Aufsichtsrats: Sebastian Krause</font><br><font size="3" face="serif">Geschäftsführung: Gregor Pillen (Vorsitzender), Nicole Reimer, </font><br><font size="3" face="serif">Gabriele Schwarenthorer, Christine Rupp, Frank Theisen</font><br><font size="3" face="serif">Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht<br>Stuttgart, HRB 14562 / WEEE-Reg.-Nr. DE 99369940</font><br><br><br><font size="3" face="serif">-----Original Message-----</font><br><font size="3" face="serif"><b>From</b></font><font size="3" face="serif">: Stephan Graf <</font><a href="mailto:Stephan%20Graf%20%3cst.graf@fz-juelich.de%3e"><font size="3" color="#0000FF" face="serif"><u>st.graf@fz-juelich.de</u></font></a><font size="3" face="serif">></font><br><font size="3" face="serif"><b>Reply-To</b></font><font size="3" face="serif">: gpfsug main discussion list <</font><a href="mailto:gpfsug%20main%20discussion%20list%20%3cgpfsug-discuss@gpfsug.org%3e"><font size="3" color="#0000FF" face="serif"><u>gpfsug-discuss@gpfsug.org</u></font></a><font size="3" face="serif">></font><br><font size="3" face="serif"><b>To</b></font><font size="3" face="serif">: gpfsug-discuss <</font><a href="mailto:gpfsug-discuss%20%3cgpfsug-discuss@gpfsug.org%3e"><font size="3" color="#0000FF" face="serif"><u>gpfsug-discuss@gpfsug.org</u></font></a><font size="3" face="serif">></font><br><font size="3" face="serif"><b>Subject</b></font><font size="3" face="serif">: [EXTERNAL] [gpfsug-discuss] Protection against silent data corruption</font><br><font size="3" face="serif"><b>Date</b></font><font size="3" face="serif">: Thu, 02 Jun 2022 16:31:43 +0200</font><br><br><font size="3" face="serif">Hi,</font><br><br><font size="3" face="serif">I am wondering if there is an option in SS to enable some checking to </font><br><font size="3" face="serif">detect silent data corruption.</font><br><br><font size="3" face="serif">Form GNR I know that there is End-to-End integrity. So a checksum is </font><br><font size="3" face="serif">stored in addition.</font><br><br><font size="3" face="serif">The background is that we are facing an issue where in some files (which </font><br><font size="3" face="serif">have data replication = 2) the mmrestripefile is reporting, that one </font><br><font size="3" face="serif">block is mismatching it's copy (the storage cluster is running SS </font><br><font size="3" face="serif">without GNR).</font><br><font size="3" face="serif">We have validated that the copied block is fine, but the original one is </font><br><font size="3" face="serif">broken (and this is what is returned on read access).</font><br><font size="3" face="serif">SS right now in our installation is unable to determine which is the </font><br><font size="3" face="serif">correct one.</font><br><font size="3" face="serif">Is there any option to enable this kind of feature in SS? If not, does </font><br><font size="3" face="serif">it make sense to create an "IDEA" for it?</font><br><br><font size="3" face="serif">Stephan</font><br><br><font size="3" face="serif">_______________________________________________</font><br><font size="3" face="serif">gpfsug-discuss mailing list</font><br><font size="3" face="serif">gpfsug-discuss at </font><a href="http://gpfsug.org"><font size="3" color="#0000FF" face="serif"><u>gpfsug.org</u></font></a><br><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org"><font size="3" color="#0000FF" face="serif"><u>http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org</u></font></a><br><font size="3" face="serif">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at </font><a href="http://gpfsug.org"><font size="3" color="#0000FF" face="serif"><u>gpfsug.org</u></font></a><font size="3" color="#0000FF" face="serif"><u><br></u></font><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org"><font size="3" color="#0000FF" face="serif"><u>http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org</u></font></a></ul><tt><font size="2">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at gpfsug.org<br></font></tt><tt><font size="2"><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org">http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org</a></font></tt><tt><font size="2"> <br></font></tt><br><br><BR>
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