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How would Plex know where the duplicate file is if a drive fails?


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Curious how folder duplication would work with Plex Media Server app (Movie/TV Streaming) if a drive fails. I have a large drivepool  (80TB) with about 15 drives and if a drive ever fails SMART, it starts to offload everything off the drive per Stablebit Drivepool > Manage Pool > Balancing > Balancers > "Move un-duplicated files out of drives with SMART warnings" 

(1)   If I have 2x duplication on everything and a drive fails, how is Plex going to know both locations and be able to grab it from location 2?   

(2)  If I have 2x duplication on everything and two people stream the same file, does it sometimes grab it from location 1, and sometimes from location 2?   I guess this would be a plus since there is less chance of over-saturating a drive, but I'm sure it would take a ton of people accessing the same drive to cause that?

The reason I ask is today I had a drive fail SMART so Drivepool started to remove media from the drive per the auto setting.  A friend tried streaming an educational TV show and it just spun forever and wouldn't play (probably because it started to offload the media from this drive).  The media she attempted to stream was not setup under 2x redundancy.   In this scenario if I had 2x redundancy enabled,  how would Plex have actually succeeded in streaming it?  How would it know where the 2nd location is to pull from, if it's just told "TV Shows are under "T:\TV\Mythbusters."  

Usually when Plex has 2 of the same file, it shows a "2" in the corner, but I don't see "2" for any of the media that I do have 2x redundancy on, so I'm not sure how 2x redundancy would have successfully streamed it?  I don't want to duplicate the whole TV Show drive (30TB) if it wouldn't actually fix a scenario as described.  If it would, then I need to purchase some more storage. Hopefully I made it clear enough to understand.  Thanks in advance.

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I don't know Plex but normally any application that accesses files through the Pool is neither redundancy nor phyiscal location aware. It is not Plex that needs to know what drive has the data, DrivePool does that for you.

I think that if you have duplication then, yeah, it may read from multiple drives. Mind you, I have never really experienced a performance gain because of this but some say they have.

I guess that when a drive gets removed/offloaded that that may impact performance somewhat but AFAIK, it is a lower priority task and should hardly interfere with regular I/O, especially if you have the option to prioritise network I/O turned on. So I am not sure what would have caused the non-performance.

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UmFriend is correct Plex only sees what DP presents to it as it sees the pool drive (virtual) and not the disks

if a drive fails then the "other" copy is used so Plex or any app carries on as normal if you have duplication on. As for the streaming error - could be a number of reasons - one of which is the file was damaged by the disk failure or the disk was removed and plex then could not find the file.......

If you have read striping on you can see in DP that it uses both disks at various times when presenting a file to application X - this does not radically change the speed of the read but if one disk slows (as other files are also being accessed at the same time on one disk) the other will be used etc etc. The speed of the read is the speed of the disk being used - no magic here.

Basically if you want redundancy then you need more space for the duplication or be selective in which shows you duplicate - but you will need more space at some point.

 

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