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From: chris@mimsy.umd.edu (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: panic() design question
Message-ID: <26197@mimsy.umd.edu>
Date: 25 Aug 90 04:37:35 GMT
References: <24280@adm.BRL.MIL>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 18

In article <24280@adm.BRL.MIL> dave@tis.com (David I. Dalva) asks
why the 4BSD and SysVR? (neither release number nor platform mentioned,
although these have a great deal of significance) kernels attempt to
sync the disks on a call to panic:

>Why is it that panic calls sync() (or update()) before the system is
>halted, when data structures may be messed up causing further damage to
>the filesystem?

In general, the panic is due to something relatively minor, and the
sync makes things better instead of worse.  Very occasionally (especially
after mucking with the filesystem code :-) ) it has the opposite effect,
but overall the sync was deemed to be a win.

(Anyway, system developers can always disable it temporarily.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 405 2750)
Domain:	chris@cs.umd.edu	Path:	uunet!mimsy!chris