hi Stephan, there is, see mmchconfig man page :
nsdCksumTraditional 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. (Traditional in this context means that the NSD client and server are configured with IBM Spectrum Scale rather than with IBM Spectrum Scale RAID. The latter is a component of IBM Elastic Storage Server (ESS) and of IBM GPFS Storage Server (GSS).) 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 server. A checksum error triggers a request to retransmit the message. 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 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. 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. Note: * Enabling this feature can result in significant I/O performance degradation and a considerable increase in CPU usage. * To enable checksums for a subset of the nodes in a cluster, issue a command like the following one: mmchconfig nsdCksumTraditional=yes -i -N <subset-of-nodes> The -N flag is valid for this attribute. -- Mit freundlichen Grüßen / Kind regards Achim Rehor Technical Support Specialist Spectrum Scale and ESS (SME) Advisory Product Services Professional IBM Systems Storage Support - EMEA [email protected]<mailto:[email protected]> +49-170-4521194 IBM Deutschland GmbH Vorsitzender des Aufsichtsrats: Sebastian Krause Geschäftsführung: Gregor Pillen (Vorsitzender), Nicole Reimer, Gabriele Schwarenthorer, Christine Rupp, Frank Theisen Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart, HRB 14562 / WEEE-Reg.-Nr. DE 99369940 -----Original Message----- From: Stephan Graf <[email protected]<mailto:stephan%20graf%20%[email protected]%3e>> Reply-To: gpfsug main discussion list <[email protected]<mailto:gpfsug%20main%20discussion%20list%20%[email protected]%3e>> To: gpfsug-discuss <[email protected]<mailto:gpfsug-discuss%20%[email protected]%3e>> Subject: [EXTERNAL] [gpfsug-discuss] Protection against silent data corruption Date: Thu, 02 Jun 2022 16:31:43 +0200 Hi, I am wondering if there is an option in SS to enable some checking to detect silent data corruption. Form GNR I know that there is End-to-End integrity. So a checksum is stored in addition. The background is that we are facing an issue where in some files (which have data replication = 2) the mmrestripefile is reporting, that one block is mismatching it's copy (the storage cluster is running SS without GNR). We have validated that the copied block is fine, but the original one is broken (and this is what is returned on read access). SS right now in our installation is unable to determine which is the correct one. Is there any option to enable this kind of feature in SS? If not, does it make sense to create an "IDEA" for it? Stephan _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at gpfsug.org http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org
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