*BSD News Article 74726


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From: tedm@cpinc.com
Newsgroups: comp.os.linux.hardware,comp.os.ms-windows.win95.misc,comp.os.os2.setup.misc,comp.unix.bsd.freebsd.misc
Subject: Re: HELP: Can I mix memory speeds
Date: 26 Jul 1996 06:18:14 GMT
Organization: Symantec Corporation
Lines: 38
Message-ID: <4t9nv6$ge5@symiserver2.symantec.com>
References: <4sr0bg$4ae@uriah.heep.sax.de> <stephenkDuxI2x.B5M@netcom.com> <4t0ur6$7bn@uriah.heep.sax.de> <stephenkDv2n7u.327@netcom.com>
Reply-To: tedm%toybox@agora.rdrop.com
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In <stephenkDv2n7u.327@netcom.com>, stephenk@netcom.com (Stephen Knilans) writes:

[some deleted]

>
>Parity is NOT a panacea no matter WHAT anyone will say.  It is merely a check
>bit that says something MIGHT be wrong with the memory.  Obviously, since it
>is only one bit, it can't even do THAT 100% right 100% of the time.  A bad

[more deleted]

I agree that ECC memory is much better than Parity, but Parity is much better
than none at all.

The biggest problem with memory errors is that they are insidious.  If I backup
my data every day, and I have non-parity memory, I could slowly be corrupting
my data over a period of months.  By the time that I discover what is going on,
my backups are hosed as well as the system.

I'd much rather have my system come to a crashing halt necessitating a restore
from backup.  At least then I know there is a problem and I can replace the
hardware.

Considering that ECC is much more expensive than Parity, and parity is only a
little more expensive than non-parity memory, it is really a question of how
much your time is worth.  Like you, I rarely see parity problems today, but
I used to see them a lot a couple years ago.  I consider the probability of a 
memory error so low now that it is worth gambling that I'll have to recover
from a hard system crash, instead of paying the extra for ECC memory.

Given all that, most of the cheaper Pentium motherboards sold today don't
support Parity anyway.  This is not a problem with the PCI chipset as some
have said, as a matter of fact according to Intel, the famous version of the
Triton chipset that doesen't support parity is no longer in production anyway.
The problem is MB manufacturers who use PCI chipsets that support parity,
but to save a few cents don't bother putting the traces on the motherboard!

Ted