[Crash-utility] what is recommended dump level

[Tokuhisa Inagaki]

Hi, all.

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.