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Requesting check on data migration approach


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Hi -- new user. After some reading, am planning following and would like feedback:




New server, using UnRAID 6, mix of 2 and 4 TB drives (18 TB total) already in server.


Also have two 8 TB drives w/data I want to preserve (total data is ~6 Gig across both 8 TB drives, to be clear), and incorporate into an Array.


Plan (feedback welcome)


  1. Setup Array with the 2s and 4s (using a 4 as Parity)
  2. Add the 8 TBs as Unassigned
  3. Copy 8 TB data --> array using something like the Docker Dolphin image
  4. Add one of the 8 TBs as Parity, the other to the Array


Does above make sense? I can attach the 8 TBs w/USB, as well -- just seems easier to just plug them in where I'll want them eventually and copy from there.

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Regarding your step 3: " Copy 8 TB data --> array using something like the Docker Dolphin image"


I experienced severe slow-down and fragmentation with Dolphin (and Krusader) when migrating a large amount of data. Mc from console has fragmentation but no slow-down.

The worst one was when fragmentation went from 3-ish% to 50+% (pretty much every new file was fragmented) and speed started at about 120+MB/s but went down to 10MB/s after about 2-3 hours. The docker was left running alone overnight with nothing else interfering + migration was between 7200rpm disks + turbo write was on + no SMART error.


I would recommend for a very large amount of data to use the Userscript plugin + rsync (with whatever rsync options you deem necessary). I have never had any slow-down (average speed in line with typical performance) and fragmentation only went up by a tiny amount (just did about 10TB worth of moving things around to prep things for a new server plan).


Oh and don't forget to turn on turbo write.

And if you don't mind data being distributed across all disks, Most Free allocation may offer some speed advantage.

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