<font size=3 face="sans-serif">Generally you should not run mmfsck unless
you see MMFS_FSSTRUCT errors in your system logs. To my knowledge
online mmfsck only checks for a subset of problems, notably lost blocks,
but that situation does not indicate any problems with the file system.</font><br><br><font size=3 face="sans-serif">Fred<br>__________________________________________________<br>Fred Stock | IBM Pittsburgh Lab | 720-430-8821<br>stockf@us.ibm.com</font><br><br><br><br><font size=1 color=#5f5f5f face="sans-serif">From:
</font><font size=1 face="sans-serif">"Simon Thompson
(IT Research Support)" <S.J.Thompson@bham.ac.uk></font><br><font size=1 color=#5f5f5f face="sans-serif">To:
</font><font size=1 face="sans-serif">gpfsug main discussion
list <gpfsug-discuss@spectrumscale.org></font><br><font size=1 color=#5f5f5f face="sans-serif">Date:
</font><font size=1 face="sans-serif">10/11/2017 06:32 AM</font><br><font size=1 color=#5f5f5f face="sans-serif">Subject:
</font><font size=1 face="sans-serif">Re: [gpfsug-discuss]
Checking a file-system for errors</font><br><font size=1 color=#5f5f5f face="sans-serif">Sent by:
</font><font size=1 face="sans-serif">gpfsug-discuss-bounces@spectrumscale.org</font><br><hr noshade><br><br><br><tt><font size=2>OK thanks,<br><br>So if I run mmfsck in online mode and it says:<br>"File system is clean.<br>Exit status 0:10:0."<br><br>Then I can assume there is no benefit to running in offline mode?<br><br>But it would also be prudent to run "mmrestripefs -c" to be sure
my<br>filesystem is happy?<br><br>Thanks<br><br>Simon<br><br>On 11/10/2017, 11:19, "gpfsug-discuss-bounces@spectrumscale.org on
behalf<br>of UWEFALKE@de.ibm.com" <gpfsug-discuss-bounces@spectrumscale.org
on<br>behalf of UWEFALKE@de.ibm.com> wrote:<br><br>>Hm , mmfsck will return not very reliable results in online mode,<br>>especially it will report many issues which are just due to the transient<br>>states in a files system in operation.<br>>It should however not find less issues than in off-line mode.<br>><br>>mmrestripefs -c does not do any logical checks, it just checks for<br>>differences of multiple replicas of the same data/metadata.<br>>File system errors can be caused by such discrepancies (if an odd/corrupt<br>>replica is used by the GPFS), but can also be caused (probably more<br>>likely) by logical errors / bugs when metadata were modified in the
file<br>>system. In those cases, all the replicas are identical nevertheless<br>>corrupt (cannot be found by mmrestripefs)<br>> <br>>So, mmrestripefs -c is like scrubbing for silent data corruption (on
its<br>>own, it cannot decide which is the correct replica!), while mmfsck
checks<br>>the filesystem structure for logical consistency.<br>>If the contents of the replicas of a data block differ, mmfsck won't
see<br>>any problem (as long as the fs metadata are consistent), but mmrestripefs<br>>-c will. <br>><br>> <br>>Mit freundlichen Grüßen / Kind regards<br>><br>> <br>>Dr. Uwe Falke<br>> <br>>IT Specialist<br>>High Performance Computing Services / Integrated Technology Services
/<br>>Data Center Services<br>>--------------------------------------------------------------------------<br>>-----------------------------------------------------------------<br>>IBM Deutschland<br>>Rathausstr. 7<br>>09111 Chemnitz<br>>Phone: +49 371 6978 2165<br>>Mobile: +49 175 575 2877<br>>E-Mail: uwefalke@de.ibm.com<br>>--------------------------------------------------------------------------<br>>-----------------------------------------------------------------<br>>IBM Deutschland Business & Technology Services GmbH / Geschäftsführung:<br>>Thomas Wolter, Sven Schooß<br>>Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart,<br>>HRB 17122 <br>><br>><br>><br>><br>>From: "Simon Thompson (IT Research Support)" <S.J.Thompson@bham.ac.uk><br>>To: "gpfsug-discuss@spectrumscale.org"<br>><gpfsug-discuss@spectrumscale.org><br>>Date: 10/11/2017 10:47 AM<br>>Subject: [gpfsug-discuss] Checking a file-system
for errors<br>>Sent by: gpfsug-discuss-bounces@spectrumscale.org<br>><br>><br>><br>>I'm just wondering if anyone could share any views on checking a<br>>file-system for errors.<br>><br>>For example, we could use mmfsck in online and offline mode. Does online<br>>mode detect errors (but not fix) things that would be found in offline<br>>mode?<br>><br>>And then were does mmrestripefs -c fit into this?<br>><br>>"-c<br>> Scans
the file system and compares replicas of<br>> metadata
and data for conflicts. When conflicts<br>> are
found, the -c option attempts to fix<br>> the
replicas.<br>>"<br>><br>>Which sorta sounds like fix things in the file-system, so how does
that<br>>intersect (if at all) with mmfsck?<br>><br>>Thanks<br>><br>>Simon<br>><br>>_______________________________________________<br>>gpfsug-discuss mailing list<br>>gpfsug-discuss at spectrumscale.org<br>></font></tt><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e="><tt><font size=2>https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e=</font></tt></a><tt><font size=2><br>><br>><br>><br>><br>><br>>_______________________________________________<br>>gpfsug-discuss mailing list<br>>gpfsug-discuss at spectrumscale.org<br>></font></tt><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e="><tt><font size=2>https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e=</font></tt></a><tt><font size=2><br><br>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></font></tt><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e="><tt><font size=2>https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwIFAw&c=jf_iaSHvJObTbx-siA1ZOg&r=p_1XEUyoJ7-VJxF_w8h9gJh8_Wj0Pey73LCLLoxodpw&m=V8K9eELGXftg3ELG2jV1OYptzOZ-j9OdBkpgvJXV_IM&s=MdJhKZ9vW4uhTesz1LqKiEWo6gZAEXjtgw0RXnlJSgY&e=</font></tt></a><tt><font size=2><br><br></font></tt><br><br><BR>