Im preclearing a new parity drive.

i will place the old parity to the data.. Do i need to preclear it also?

or can i format it or just leave it alone and add it?

Unless you want to test it for some reason, no need to preclear. However, if you add a disk that is not cleared to the array, unRAID will clear it before you can format it. An added disk must be clear so parity will remain valid. A clear disk is all zeros so has no impact on parity.

That is the "standard" way of doing things. There is another. See here:

 

Ok so no need to preclear old parity

i said the new parity is preclearing now.. During this can i already put in the old drive as data or should i wait till preclearing is done and the new parity is added as parity?

Just now, skank said:

During this can i already put in the old drive as data or should i wait till preclearing is done and the new parity is added as parity?

You can and that will avoid clearing the old parity, but it will also put the array at risk if there's a problem during the new parity sync, depends on how important is your data and/or if you have backups, keeping the old parity intact and the array data unchanged during the new sync allows you to re-use the old parity if there's a problem.