Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!nrl-cmf!cmcl2!rocky8!cucard!ccnysci!alexis
From: alexis@ccnysci.UUCP (Alexis Rosen)
Newsgroups: comp.sys.mac.programmer
Subject: Re: A Few Technical Questions
Message-ID: <936@ccnysci.UUCP>
Date: 21 Oct 88 03:38:20 GMT
References: <940@uvm-gen.UUCP> <3f185fcb.129dc@blue.engin.umich.edu>
Reply-To: alexis@ccnysci.UUCP (Alexis Rosen)
Lines: 34

In article <3f185fcb.129dc@blue.engin.umich.edu> mystone@caen.engin.umich.edu
(Dean Yu) writes:
>In article <940@uvm-gen.UUCP>, chaffee@uvm-gen.UUCP (Alex D. Chaffee) writes:
>> (2)
>> If I take the time to select "Shut Down" from the Finder, the next
>> time I boot my hard disk (an internal HD20SC - in my Mac SE with1 MB
>> RAM) it takes maybe a second to display the "Welcome to Macintosh"
>> dialog.  If I don't select Shut Down, the drive is active for more
>> than a minute - I've got a very full hard disk - before it continues.
>> I'd like to know, first of all, what the HD thinks it's doing during
>> this interminable pause; second, exactly what "Shut Down" does [...]

>  What's happening here is that when you shut down, if you're not parking
>the heads, it's at least moving them closer to the boot blocks.  If you just
>restart, it leaves the heads where they wre when you restarted, so it has to
>seek all over the platters for the boot blocks.  And considering the speed of
>an HD20, even an SC...  (Sorry, I couldn't resist!  ;)  )  


You can't be serious! Even the SC's access time is measured in milliseconds.

In fact, ShutDown calls UnMountVol, which writes some sort of status bit to the
drive before it closes everything down. When the volume is first mounted (or
sometime around then, I don't remember exactly) a dirty bit is set. When it is
unmounted (or put offline, maybe?) the dirty bit is cleared. This bit may or
may not be associated with the catalog and extents files. I just looked in IM
and couldn't find anything on this, so I assume I read it in some tech note.

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Alexis Rosen                       alexis@dasys1.UUCP  or  alexis@ccnysci.UUCP
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