Check or Sync Parity

[pokes]

When adding a second parity disk (parity 2) it appeared that Unraid did writing to it, & reading from the original parity (disk 1)

I didn't see any data disk activity

 

So did it just do a parity sync between the 2 parity disks - comparing parity with stored parity

or did it do a parity check, read all the data disks and the parity disk, comparing parity with stored parity

 

If it only did a parity sync, should I now do a parity check ?

& does a parity check take more time to complete with 2 parity disks ?

 

 

 

 

[itimpi]

2 hours ago, pokes said:

When adding a second parity disk (parity 2) it appeared that Unraid did writing to it, & reading from the original parity (disk 1)

I didn't see any data disk activity

Parity2 cannot be built without reading all the data drives as it uses a different calculation to that used for parity1 so not sure why this did not show up  

 

2 hours ago, pokes said:

does a parity check take more time to complete with 2 parity disks ?

 

Not unless you have a really low spec CPU that struggles calculating the parity values fast enough.  All modern CPUs will be constrained via the drive speeds so it is the size of the largest parity drive that determines the time taken.

 

[pokes]

11 minutes ago, itimpi said:

so not sure why this did not show up  

It took almost 10 hours & I only watched it a bit at the start

 

11 minutes ago, itimpi said:

unless you have a really low spec CPU

i5 4690 / 8GB DDR3

Edited April 19, 2021 by pokes