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This topic comprises 4 pages: 1 2 3 4
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Author
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Topic: Dolby DSS 200 Array Degraded and Interrupted Playback
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Manny Knowles
"What are these things and WHY are they BLUE???"
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Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002
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posted 12-10-2013 07:36 PM
A DSS200 is capable of functioning even if one hard drive goes bad. I know this because I have run shows with a degraded array, due to one faulty drive.
If your array is degraded to the point where you are having failures, then you might have more than one dead drive (or, possibly, some other problem that I haven't encountered).
My first degradation (and my only one, so far) occurred during the warranty period. So, yes, hard drives can die young.
When you replace the bad drive(s), do yourself a favor and order an extra one to keep on-hand as a spare. Steve Guttag made sure we were provided with a spare drive as part of our package, and I was glad to have it ready when it was needed. (Thanks, Steve!) The dead drive was replaced by Dolby, so that is now the spare drive.
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Marco Giustini
Film God
Posts: 2713
From: Reading, UK
Registered: Nov 2007
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posted 12-11-2013 03:54 AM
No, a DSS system won't play with only two drives, your operator must be mistaken.
Probably the system was badly handled when being shipped. An array degrades when a disk fails. It could degrade because the disk has a temporary glitch - always worth try to rebuild the array if the disk does not show any - or few - bad sectors before replacing the disk - but in general that means you have a bad disk. Check the reallocated sectors count as I suggested.
RAID stands for Redundant Array of Independent Disks. Basically if you have 4 HDD of 1TB each the system will write the information on three disks only; the fourth will be use as a parity disk. That is, say disk 1-2-3 are the data disks and disk 4 is the parity one, if disk 2 fails the system can extrapolate the missing information using the data contained in disk 4 (it does not work like that but just to give you an idea). Your storage capacity of the RAID will be only 3TB.
If ONE drive fails, the system is still perfectly capable of accessing all the information - one disk will also be redundant. If TWO drives fail, the information on your RAID will be lost permanently.
When that happen you'll have to replace the two drives and reinstall the OS on the system. You'll lose your content and some of your settings.
When a disk fails the RAID controller should be capable of assessing that and should disconnect the faulty disk before it causes trouble but that doesn't happen all the time and you may end up with an interrupted show before the controller takes the disk out of service.
Check the number of reallocated sectors on all your servers, replace anything with more than 10 bad sectors (this is what Dolby recommends, from my point of view a brand new drive should show ZERO bad sectors). If servers are brand new Dolby will pay for them.
When you replace a drive the system will realise that one drive does not contain any information and will start the "rebuild" process which is recreating the data on the new drive based on the data on the other three drives. The process will take several hours. Can be done during playback but it's not recommended, better to replace a drive early in the morning or last thing in the night.
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Marco Giustini
Film God
Posts: 2713
From: Reading, UK
Registered: Nov 2007
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posted 12-12-2013 06:37 AM
Mohd,
You probably misunderstood, a server cannot run without HDDs. If that was what your projectionist and installer actually suggested... get rid of them, quickly!
I wouldn't bother for a second, if your disk is showing bad sectors - did you check that? - I would ask for a replacement straight away. Your server is 2 weeks old!
Turning the servers off at night won't hurt them in the short term. It's proved that on the long term your HDDs won't like it and will fail sooner than when the servers are on 24/7. But at this moment this is not the cause of your problem.
Anyway, if a disk is showing bad sectors you cannot cure them. You can rebuild the array if it says "degraded". It should happen automatically, or just go under SYSTEM/Server tools and click on REBUILD. To be on the safe side, do it overnight, after the last show.
If the array is NOT degraded, it does not need to be rebuilt. If any of the HDDs is showing bad sectors, replace it.
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