So I recently bought two Seagate 8TB shingled drives.

 

One for parity, one for data.

 

Ran two pre-clears, the results seemed ok to me.

 

So I began the format of the new data drive, and after selecting the other drive as parity, started the array and the parity sync began.

 

It appears that's not a problem - but I was just a bit surprised that it could parity sync and format a new drive at the same time?

Yes, you can do that at the same time.  I wouldn't actually recommend it, as it slows both operations down due to the excessive seeks ... but the format is a relatively quick operation, so it will be finished fairly soon, and then the parity sync will run at full speed.

 

 

Parity works at the bit level, format works at the file system level.  Parity doesn't care about files and file systems, they are all just 0's and 1's to it.  You can read more about how parity works in the FAQ and the new unRAID Manual 6.

Ok thanks guys.

 

I had just thought it was strange that it could be computing parity across 8(9) drives, while one of the data drives was being formatted.

 

I mean I'm glad it's not a problem - I just was a little bewildered. 

 

 

After the format finished (I presume that's long done) you can even "use" the array ==> i.e. copy data to or from it, etc.  But as I noted above, it's NOT a good idea to do this, as it causes a lot of disk thrashing (head movements).