Date: Sat, 14 Aug 1999 14:04:04 -0700 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: Mike Meyer <mwm@phone.net> Cc: stable@FreeBSD.ORG Subject: Re: Random disk read problems Message-ID: <199908142104.OAA75747@cwsys.cwsent.com> In-Reply-To: Your message of "Fri, 13 Aug 1999 22:28:56 PDT." <Pine.BSF.4.10.9908132223010.94664-100000@guru.phone.net>
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In message <Pine.BSF.4.10.9908132223010.94664-100000@guru.phone.net>,
Mike Meye
r writes:
> I've been shuffling some data around in preperation for archiving
> it. Being a bit paranoid, I tend to md5 sum the stuff at both ends,
> and then verify the checksums.
>
> I'm getting random differences. I.e. - the diff of the md5 sums will
> turn up a file or two that are different. Running diff or cmp on them
> by hand - and they're the same. Likewise, running md5 on them by hand
> turns up correct sums.
>
> This worries me. I'm running an older version of 3.2-stable on a
> SuperMicro motherboard with 256Meg of ram and a Seagate ST39173W SCSI
> drive. Is this something that udpating the OS might fix, or am I
> seeing evidence of hardware problems (but I'm not seeing anything in
> syslog!), or possibly bugs in both diff and md5?
I had a similar problem with a SCSI Zip drive attached to a 1542CF,
primarily when the Zip drive was being used simultaneously while other
SCSI devices were using the SCSI bus. In my case, corrupted data was
being written to the Zip drive. Replacing the 1542CF with a 2940UW
solved the problem. In the mean time I've reinstalled the 1542CF and
only attached the Zip drive to it, leaving 2 SCSI disks, a CDROM drive
and a 4mm DAT attached to the 2940UW. This configuration has worked
for a number of months without problems.
I've been told that 1542's do not work well with multi-user/multi-taskin
g O/S's. I'm not sure what SCSI controller you're using. Could it be
that your controller is corrupting data when it is "very" busy?
Other than that, additional information will be needed to diagnose the
problem, including a uname -a, dmesg output, and a copy of your kernel
config file posted to this list.
Regards, Phone: (250)387-8437
Cy Schubert Fax: (250)387-5766
Open Systems Group Internet: Cy.Schubert@uumail.gov.bc.ca
ITSD Cy.Schubert@gems8.gov.bc.ca
Province of BC
"e**(i*pi)+1=0"
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