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Author Topic: Dolby DSS 200 Array Degraded and Interrupted Playback Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 12-12-2013 04:00 PM                     Marcel On a Dolby server the cat 862 is powered from the main PSU, rebooting the server by software won't fully reset it. A full shutdown every now and then is recommended. I may agree with your statement, but if your hard drive is 2 weeks old I can't see how a few bad sectors could be acceptable. If the drive shows a few bad sectors over its life, it's acceptable - as long as they're stable If a drive reaches 30.000 hours and shows 50 bad sectors, I would replace it. Its unlikely a brand new replacement lasts less time than a 30.000hrs unit.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 12-12-2013 04:56 PM                     quote: Marco Giustini On a Dolby server the cat 862 is powered from the main PSU, rebooting the server by software won't fully reset it. A full shutdown every now and then is recommended. That might be the solution if your Media Block is causing the troubles, but here it's clearly a RAID related issue. quote: Marco Giustini I may agree with your statement, but if your hard drive is 2 weeks old I can't see how a few bad sectors could be acceptable. Why not? The whole idea of modern hard drive design is that sectors that become bad are being relocated. Not one drive that rolls of the production line is entirely flawless. So what does it matter if a drive has two or three relocated sectors right from the start if they do not increase over time? This drive is operating perfectly fine, any replacement has no guarantee to be any better.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 12-12-2013 06:50 PM                     I understand that the drive has a hidden area for bad sectors which are expected over its lifetime. All bad sectors are reallocated over this area. When the area is full then the drive start marking new bad sectors as 'not available'. Unless on Server-graded drives this is not the case that means that one bad sector is not actually one. Anyway, I would not allow a single bad sector on a brand new drive. That's what I'd do. Those machines - and those drives - are too darn expensive for me to be relaxed on bad sectors! When the drive gets old, I think it's wiser to invest a little money in replacing it when it shows a number of bad sectors. If we lose a show because of it it's good money and you'll have to replace the disk anyway at some point so you're really saving pennies. On my computer it's another story, I can keep an eye on the drive and live with some glitches, but I would not advise a customer not to replace the drive unless the number of bad sectors quicly increase. Most cinemas don't have a projectionist, this kind of quality control is simply not achievable. Sure, removing the power from this server won't cure the bad disk, but when a problem shows up a power cycle is always recommended and most of the time fixes the problem - that's why we recommend a full shutdown every now and then, I believe I'm not the only one recommending it.  |  IP: Logged Gavin Lewarne Master Film Handler Posts: 278 From: Plymouth, UK Registered: Aug 2009 posted 12-12-2013 07:58 PM                     dss200 here, 13 months old, came with the factory fit hitachi drives. UPS power reboot once a week (to totally cut power for a few seconds) 0 bad sectors on all 4 drives. Server is left on 24/7 on a good UPS and have never had any sort of raid related warnings or errors show up in the logs let alone needing a rebuild. I was expecting at least some bad sectors by now but seems we have a very reliable trouble free unit. Its only ever had 1 real glitch and that was solved by replacing the silly blue link cable. I was half expecting to have at least some raid related troubles by now as we generally only ever have a maximum of 4 films stored, and I believe the XFS file system used on the content partition will always try to write from the beginning of the partition so I imagine we are using the same few hundred GB of space on all the drives over and over again  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 12-12-2013 10:05 PM                     Give it time.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 12-12-2013 10:52 PM                     quote: Marco Giustini Anyway, I would not allow a single bad sector on a brand new drive. That's what I'd do. Those machines - and those drives - are too darn expensive for me to be relaxed on bad sectors It is unreasonable to expect/demand a replacement from any server manufacturer on a new drive with a few bad sectors. As long as they aren't suddenly increasing noticeably, there is no problem.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 12-13-2013 05:54 AM                     Ok, maybe I'm a little too inflexible here. But what would you do if your drive out of the box had 30 bad sectors? I think Dolby would replace it, and I'd have it replaced.  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 12-13-2013 08:43 AM                     Has Hitachi's quality moved on from the days when their Deskstar drives were known as Deathstars?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 12-13-2013 08:48 AM                     Hitachi does not produce hard drives anymore, since 2011. And the 'Deathstars' were made by IBM when the product line was not Hitachi's. - Carsten  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 12-13-2013 12:43 PM                     I wouldn't worry about 30 sectors if it wasn't increasing rapidly.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 12-13-2013 03:20 PM                     Wouldn't be easier to ask Dolby to replace it? How do you find time to monitor the customers' drives to check whether the drive has to be replaced or not? Time is money, the disk is under warranty, Dolby would replace it. Why wasting time?  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 청주시, 경북도, South Korea Registered: Mar 2007 posted 12-13-2013 04:22 PM                     Also, SMART errors tell you that they relocated the data to one of the known good sectors, which may or may not indicate that the original sector is actually bad. There can be software issues that cause an error in reading the data that causes it to be relocated when the actual sector itself wasn't bad.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 12-13-2013 04:29 PM                     And are you willing to wait till the customer calls reporting that they had to cancel a show because the picture was stuttering to verify that? I see your point, but I'm not sure I agree with that.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 12-13-2013 04:38 PM                     IF I had customers complaining about stuttering images with a low relocated error count, I'd change my position. The fact is, I haven't. There has been no demonstrated reason for changing out a drive with a low error count (unless it is rising rapidly). As you say, time is money...who pays for the time it takes to order a replacement, send back the "defective" drive that works fine and changes the drive? I can guarantee you that it takes less time, effort and money to check the status of the drives every once in a while. We do it for all of our customers. Checking reallocated sectors takes very little time on most all servers. Again, seeing "errors" in the logs, to me, is a bigger indicator of a drive problem. But hey...handle your service your way...nobody is saying you are wrong. We try to provide our customers with zero issues at all times (not always successful but mostly so)...like everything else, we concentrate on what we have found to be more problematic or leading indicators of failures and catch them when they happen...a drive with a dozen reallocated sectors hasn't shown itself to be a problem. A drive with 50 reallocated sectors today that had 25 yesterday...IS a problem.  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 청주시, 경북도, South Korea Registered: Mar 2007 posted 12-13-2013 04:40 PM                     I don't see where I implied that. And there are ways to find determine if a sector is actually bad. Heck, there's even software out there to help fix the sectors that are actually bad.  |  IP: Logged

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