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From: jas@ernie.Berkeley.EDU (Jim Shankland)
Newsgroups: comp.databases,comp.sys.hp
Subject: Re: Corrupted database in Oracle
Keywords: Oracle HP-UX crash
Message-ID: <28308@ucbvax.BERKELEY.EDU>
Date: 7 Mar 89 04:38:44 GMT
References: <115@geysir.os.is> <735@hscfvax.harvard.edu>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: jas@ernie.Berkeley.EDU.UUCP (Jim Shankland)
Organization: University of California, Berkeley
Lines: 31

In article <735@hscfvax.harvard.edu> pavlov@hscfvax.harvard.edu (G.Pavlov) writes:
>In article <115@geysir.os.is>, eik@os.is (Einar Kjartansson) writes:
[about how Oracle has repeatedly soiled its filesystem on an HP 9000/840,
causing loss of several days' work each time ...]

>  I fail to understand how anyone can seriously consider purchasing a DBMS 
>  that insists on "improving" performance by bypassing a given system's file
>  management facility.  It's a cheap method for the vendor, but as the above
>  has discovered, may be very expensive to the user....  The user is
>  now faced with a big black box (a large extent of disk
>  space known only as a huge "file" to the system) which is difficult to pene-
>  trate with the usual system debugging tools and has to be overwritten in
>  toto from backup.

There are some persuasive reasons for rolling your own filesystem when
you're implementing a DBMS, especially on UNIX, whose filesystem serves
DBMS implementors poorly.  The problem is not just speed, but reliability.
Ideally, you'd like the UNIX vendors to provide reasonable file system
services; but if they don't, you're stuck with either using the miserable
services they provide, or rolling your own.

Of course, if you do roll your own, you need to do the whole job.  That
means being damned sure it's robust and correct, *and* providing
filesystem debugging, repair, and analysis tools.  Doing the job
right is by no means "a cheap method for the vendor."

Jim Shankland
jas@ernie.berkeley.edu

"There is no help, for all these things are so,
 And all the world is bitter as a tear."