hey, i currently have 3 data drives and 1 Redundancy drive, size is 2TB

i am planning to get 3 (maybe 4 and have 1 as cold spare) drives with above 6TB capacity, so one drive can fit all the data i already have, i think i will set 2 drives as redundancy and 1 as data

 

so how does unraid handle removing drives in favor of less higher capacity drives?

 

i am currently at my unraid drive license limit, i assume i should replace my current redundancy drive, then one of my data drives

if i remove a drive, will unraid automatically just populate the data for the missing drive to the other drives in the array or is that i should do manually beforehand?

Draw a deep breath at this point.  Slow down and analyze YOUR situation.  First thing, you (currently) planning on buying at least three drives initially.  You probably have a limitation on the number of drives that you can put into your server.  Now recognize that most modern Hard drives have a five-to-nine years (minimum) life in typical Unraid type of operation. 

 

What is your expected rate (per year) of additional storage space needed?

 

What is the state of your current finances?  (Do you have lots of money to spend freely?)

 

What I would look at is the current cost perTB for disk space for various size drives.  This is usually a bathtub type curve where there is a  'sweet spot'!  

 

Now put together a worksheet (Spreadsheet is a good way to do this)  with the various size drives for Parity.  You don't really want to be replacing parity drives in three-to-four years because you need more data space and data drives bigger than the current parity drives are the only way to do that. 

 

You should now have determined the size for the parity drives that you need.

 

Now, I will tell what I would do. (I actually are in the process of doing this right now on both my servers!)  I would buy the two parity types first.  Preclear them.  (You don't want to be in the middle of a drive replacement and find out you have a bad drive!!!!)     Then run a non-correcting parity check on the current array.  There should be zero errors.  (You don't want a problem with a disk during the replacement process.)  Replace one parity drive and rebuild parity.  If all goes well, replace the second parity drive. Again parity will be rebuilt.  

 

Now is decision time.  Where are you on available storage space?  If the need for extra space is immediate, replace one of the data disks and allow it to rebuild-- otherwise wait a few weeks to a few months until you  get to that point.  (Picking which disk to replace is pretty much a turkey-shoot.  Decide which one is most likely to fail.  If all other factors are equal, go with the oldest one.)   Just leave the other two data disk for now.   (A new disk is more likely to fail that a disk that has four years under its belt!)  Replace them as needed-- either disk failure or lack of storage space.   (The difference in an array failure with three disks in it is not that much different than an array with five disks.  Moving the data off a data disk may creating more problems than replacing a failed array disk!)

Edited June 15, 20242 yr by Frank1940