December 12, 2002 at 2:56 pm
One of our application providers has just helped us architect our accounting solution using SQLServer2K Enterprise on a RAID 10. (This is a Windows2K Advanced Server machine with lots and lots of horsepower, etc.)
The setup is using separate SCSI controllers and channels: one for the Operating System, one for SQL DB, one for Crystal Reports, and one for Log Files. The Log Files are being stored on an external drive.
The problem arises in that SQL reports "the Log file for Prod.db is not available" and "communication link failure." Meanwhile, the OS is saying "disk is at risk" in regards to this external drive. If we move the log files to the same SCSI controller (but a different internal drive/channel) as the SQL array RAID 10, suddenly it works.
Which would be great, save that the vendor wants us to move it back to the external drive to maximize performance. Anyone run into _anything_ like this before or have any insight into what might be going so wrong with our external log file setup??
Thanks in advance.
Ed Hunkin
December 12, 2002 at 3:10 pm
to be honest with you it sounds like a bad scsi cable something is generating to much noise and is causing the scsi bus to loose to much information an easy test is to turn the transfer rate of that channel down and see if the problem goes away or just replace the cable. It could be the card though I doubt it if it has other internal storage attached to it. Your computer doesn't know if the drives are internal or not. It is a hardware problem on some level.
Hope that helps.
Wes
December 12, 2002 at 3:29 pm
I've seen a couple issues like this. In one, as burthold mentioned, it was cheap cable (only 76% shielded) picking up RF frequencies.
The other was an incorrectly terminated channel, running on a mylex card. Somehow, the card was compensating for it initially, then loosing it later on, then re-initializing and compensating again, etc...
December 12, 2002 at 5:13 pm
Buy from here:
Steve Jones
December 13, 2002 at 8:37 am
Thanks so much to all of you.
One of our best network admins stayed up late last night hacking away at the problem, and he'd come about 99% to the conclusion that the entire problem is an incorrectly terminated channel. (The cable is very high quality.) And the two external drives are on the end of that chain of drives; the Log drive is where things terminate. We are going to attack the problem by purchasing a high-end terminator device and see if that solves the problem.
December 13, 2002 at 10:48 am
That's one of the few redeeming qualities of being contract. You get to experience such a WIDE array of issues.
December 13, 2002 at 11:08 am
Exactly. I love being able to provide a total solution or outlook on a project not just software or hardware or database. I may not be the best at any one of those things but I always know where to look for problems and how to find solid solutions.
Wes
December 18, 2002 at 11:41 am
The high quality terminator did successfully resolve the issues immediately. Thanks again to everyone that helped with your generous insight!
December 18, 2002 at 11:56 am
Wasn't a Mylex card, was it? If not, what Kind?
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