Path: utzoo!attcan!uunet!husc6!mailrus!ames!pasteur!eris.berkeley.edu!korn
From: korn@eris.berkeley.edu (Peter "Arrgh" Korn)
Newsgroups: comp.sys.next
Subject: Re: Number of writes on an optifloppy
Message-ID: <7377@pasteur.Berkeley.EDU>
Date: 14 Nov 88 06:43:09 GMT
References: <8646@spl1.UUCP> <568@poseidon.ATT.COM>
Sender: news@pasteur.Berkeley.EDU
Organization: What, me organized???
Lines: 43

In <568@poseidon.ATT.COM>, ech@poseidon.ATT.COM (Edward C Horvath) said:  
>From article <8646@spl1.UUCP>, by sarge@metapsy.UUCP (Sarge Gerbode):
>> What I'm curious about is -- is there any limit to the number of
>> writes one could reasonably expect to be able to perform on an
>> optifloppy?...

>I posed your question to one of the Sony marketing types at Unix Expo in
>NYC last week: he said he'd been asked before, and one of the engineers
>thought about it a bit, filled up a couple of envelope-backs, and
>estimated the number of writes before breakdown at 1 to 10 million.
>
>Probably enough, if the estimate is correct.

????  This is considered enough?

Lesse here.  Assuming I'm using the Optical drive as my main drive (as I
might well on the NeXT box), and I'm running my machine constantly (which
I would, unless it was in the same room as me at night and made any noise
at all), and that I run it with enough jobs to force swapping to disk, we
may have a problem here.

Let's assume I'm swapping to disk 10 times a second; I'm writing to that
same general portion of the disk constantly.  If I'm swapping 5 big programs
that's twice a second I'm hitting the same portion of disk.  2 * 60 * 60 * 24 =
172800 writes to the same part of disk a day.  That would allow me to run the 
system this hard for anywhere between 6 days and 60 days before I have to 
replace the disk.

That's not a very reassuring.


Granted NeXT is using a Canon drive vs. a Sony and I've seen no estimate
of this sort on the Canon drive vs. a fourth-hand report on a similar drive
made by a different manufacturer.  However if anything near these numbers
is the case then this generation of optical technology doesn't look ready
for Unix to me...


Peter
--
Peter "Arrgh" Korn
korn@ucbvax.Berkeley.EDU
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