Thanks Ken'ichi, Dave! > As Dave said, makedumpfile has the same risk as the partial dump > feature of diskdump. If excluding free pages and free pages linked > lists are corrupt, makedumpfile fails. So I recommend dump_level 15 > (excluding zero pages, cache pages, user data pages. not excluding > free pages) because of the same reason as diskdump. Thank you for helpful advice. I will refer to your information. > FYI: > If using RHEL5.2 or older, it is better that you update it to RHEL5.3. OK. Latest makedumpfile will be used in the future. Thanks, Toku. Ken'ichi Ohmichi wrote: > Hi, > > Dave Anderson wrote: >>> what is recommended dump level when using makedumpfile >>> (kdump)? I'm looking for explanation like this. >>> >>> ------------ from diskdump document -------------------- >>> Note that the partial dump feature has some risks. There >>> are memory management lists which are scanned for a page's >>> memory attribute, so if the list has been corrupted, the >>> scanning process may fail. For example, when specifying a >>> dump_level from 4-7 or from 12-15, the kernel's free page >>> linked lists are scanned; if the list is corrupt, diskdump >>> may hang. Furthermore, it is possible that a page type >>> that has been skipped may be necessary to fully investigate >>> the cause of some issues. Therefore, a memory collection >>> level should be selected to suit each situation. The >>> recommended level is 19, because it is easiest to determine >>> whether a page is zero-filled or if it is a page cache page, >>> and because no page lists need to be traversed. >>> ------------------------------------------------------- >>> >>> Does anyone know document describing these things >>> when using makedumpfile ? >>> >>> >>> Thanks, >>> toku. >> I don't know of any document for makedumpfile other than the >> /usr/share/doc/kexec-tools-<version>/kexec-kdump-howto.txt >> and the output of "makedumpfile -h". Neither of those has >> any caveats such as the diskdump document above, but I'm >> guessing that the same kind of issues would apply when makedumpfile >> walks page lists, the mem_map, etc. But I don't know what the >> failure mode would be, given that it's a user application as opposed >> to a kernel module. >> >> In any case, the makedumpfile maintainers are on this list >> and hopefully can shed some light on your query. > > As Dave said, makedumpfile has the same risk as the partial dump > feature of diskdump. If excluding free pages and free pages linked > lists are corrupt, makedumpfile fails. So I recommend dump_level 15 > (excluding zero pages, cache pages, user data pages. not excluding > free pages) because of the same reason as diskdump. > > > FYI: > If using RHEL5.2 or older, it is better that you update it to RHEL5.3. > > RHEL5.2's makedumpfile has a buffer-handling bug and it cannot exclude > right page occasionally. This bug has been fixed on RHEL5.3, so if using > RHEL5.2 or older you should update it. > > This bug has been fixed on makedumpfile version 1.3.0, and The following > thread is about this bug: > http://lists.infradead.org/pipermail/kexec/2008-September/002629.html > > > Thanks > Ken'ichi Ohmichi > > -- > Crash-utility mailing list > Crash-utility@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/crash-utility -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
