Just a small question on Parity.

[SmokeyColes]

Hi Morning

 

I ran a parity check and a question popped into my head.

 

My current understanding is that drives are rebuilt from a check done based on an even number of bits which can reconstruct missing data, when the data is shared across multiple drives.  The parity fills in the gaps with a check and can essentially be used to rebuild data.  This is my fairly low understanding.

 

I have set up nearly all my drives with shares in a folder stored on single drives within my pool, for example:

movies are only on drive A.  TV shows on drive C, documents will only be saved on drive e.

 

Now because of this one drive setup, I couldn't work out how data could be rebuilt, because its not rebuilding gaps of data but whole pieces of data?  

 

I guess this is a quick sanity check to ensure I haven't completely undermined the point of having the parity drives, and data shared across multiple drives. 

 

Cheers for answering what probably is a daft question.

 

Chris

 

[itimpi]

Parity has no concept of ‘data’ in the way you seem to be describing it.   It works at the raw sector level hand has no idea of the meaning of the contents of each sector, just that it is a specific bit,pattern.  It is therefore irrelevant on which drives any particular item of data resides - it is just the totality of the corresponding sector across all data drives that matters.