OK thanks, So if I run mmfsck in online mode and it says: "File system is clean. Exit status 0:10:0."
Then I can assume there is no benefit to running in offline mode? But it would also be prudent to run "mmrestripefs -c" to be sure my filesystem is happy? Thanks Simon On 11/10/2017, 11:19, "gpfsug-discuss-boun...@spectrumscale.org on behalf of uwefa...@de.ibm.com" <gpfsug-discuss-boun...@spectrumscale.org on behalf of uwefa...@de.ibm.com> wrote: >Hm , mmfsck will return not very reliable results in online mode, >especially it will report many issues which are just due to the transient >states in a files system in operation. >It should however not find less issues than in off-line mode. > >mmrestripefs -c does not do any logical checks, it just checks for >differences of multiple replicas of the same data/metadata. >File system errors can be caused by such discrepancies (if an odd/corrupt >replica is used by the GPFS), but can also be caused (probably more >likely) by logical errors / bugs when metadata were modified in the file >system. In those cases, all the replicas are identical nevertheless >corrupt (cannot be found by mmrestripefs) > >So, mmrestripefs -c is like scrubbing for silent data corruption (on its >own, it cannot decide which is the correct replica!), while mmfsck checks >the filesystem structure for logical consistency. >If the contents of the replicas of a data block differ, mmfsck won't see >any problem (as long as the fs metadata are consistent), but mmrestripefs >-c will. > > >Mit freundlichen Grüßen / Kind regards > > >Dr. Uwe Falke > >IT Specialist >High Performance Computing Services / Integrated Technology Services / >Data Center Services >-------------------------------------------------------------------------- >----------------------------------------------------------------- >IBM Deutschland >Rathausstr. 7 >09111 Chemnitz >Phone: +49 371 6978 2165 >Mobile: +49 175 575 2877 >E-Mail: uwefa...@de.ibm.com >-------------------------------------------------------------------------- >----------------------------------------------------------------- >IBM Deutschland Business & Technology Services GmbH / Geschäftsführung: >Thomas Wolter, Sven Schooß >Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart, >HRB 17122 > > > > >From: "Simon Thompson (IT Research Support)" <s.j.thomp...@bham.ac.uk> >To: "gpfsug-discuss@spectrumscale.org" ><gpfsug-discuss@spectrumscale.org> >Date: 10/11/2017 10:47 AM >Subject: [gpfsug-discuss] Checking a file-system for errors >Sent by: gpfsug-discuss-boun...@spectrumscale.org > > > >I'm just wondering if anyone could share any views on checking a >file-system for errors. > >For example, we could use mmfsck in online and offline mode. Does online >mode detect errors (but not fix) things that would be found in offline >mode? > >And then were does mmrestripefs -c fit into this? > >"-c > Scans the file system and compares replicas of > metadata and data for conflicts. When conflicts > are found, the -c option attempts to fix > the replicas. >" > >Which sorta sounds like fix things in the file-system, so how does that >intersect (if at all) with mmfsck? > >Thanks > >Simon > >_______________________________________________ >gpfsug-discuss mailing list >gpfsug-discuss at spectrumscale.org >http://gpfsug.org/mailman/listinfo/gpfsug-discuss > > > > > >_______________________________________________ >gpfsug-discuss mailing list >gpfsug-discuss at spectrumscale.org >http://gpfsug.org/mailman/listinfo/gpfsug-discuss _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at spectrumscale.org http://gpfsug.org/mailman/listinfo/gpfsug-discuss