July 18, 20178 yr As I understand it, if a parity drive goes bad, it must be replaced with a drive of equal or greater size. What about the data drives? If I have a 4TB drive that goes bad, but it only had 1TB of data on it, can I replace it with a 2TB drive? Or must it also be 4TB or equal to the parity drive size? And/or does this depend on how you rebuild it (unraid rebuilds it or I manually format and copy the files over)? Thanks!
July 18, 20178 yr 1 hour ago, manorfan said: As I understand it, if a parity drive goes bad, it must be replaced with a drive of equal or greater size. What about the data drives? If I have a 4TB drive that goes bad, but it only had 1TB of data on it, can I replace it with a 2TB drive? Or must it also be 4TB or equal to the parity drive size? And/or does this depend on how you rebuild it (unraid rebuilds it or I manually format and copy the files over)? Thanks! Actually when replacing a parity drive I think it is possible to use a smaller drive as long as the new drive is at least as large as the largest data drive. However I must admit I have never tested this so could be wrong. I could see a scenario where you have a 8TB parity drive (planning for future expansion) with the largest data drive being 4TB. If the parity drive now failed you might want to use in its place a 4TB drive you already have available. If you want to replace a data drive then the replacement must be at least as large as the drive it replaces and no larger than the smallest parity drive. It does NOT need to be as large as the parity drive (if parity is larger than the failed drive) This makes sense as parity works at the sector level and in the case you mention it has no idea where on the failed 4 TB drive the sectors that actually contained the 1TB of data are located - it blindly restores all sectors regardless of whether they contain data. The replacement drive CAN be larger (assuming it is not larger than the parity drive) as after restoring the original contents unRAID can carry out an additional step of expanding the file system to fill the drive.
July 18, 20178 yr 4 minutes ago, itimpi said: Actually when replacing a parity drive I think it is possible to use a smaller drive as long as the new drive is at least as large as the largest data drive. Correct
July 18, 20178 yr 4 hours ago, johnnie.black said: Correct Replacing parity with a smaller drive would obviously be possible with new config, but does it actually let you do this without taking that step?
July 18, 20178 yr 1 minute ago, trurl said: but does it actually let you do this without taking that step? Yes, you don't even need to make unRAID forget current parity, just stop the array, assign the smaller disk and start array to begin the parity sync.
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