Parity Check and Mover Running Concurrently

[dboonthego]

I recently added two cache disks to my system, so the cache pool stuff is sort of new to me.

 

This past Saturday, I copied about 125GB to the cache pool.  The mover is set to run at the default 3:40 AM daily.  I also have a parity check scheduled at 3:30 AM the first Sunday of every month.  I didn't realize both processes were going to execute.  Both were still churning away slowly Sunday morning.  I ended up cancelling the parity check so the mover could complete.  

 

Is it bad to execute a parity check while files are being written to the array; other than an impact on performance?  Given a choice, I would typically do one at a time.

Are there any settings I'm not aware of that would delay execution until the other has completed?

 

[queueiz]

I had the similar experience just now...

 

I copied about 200GB to a share with cache enabled (set to Yes) and when i manually invoked the mover it seems like the copy and the parity are running at the same time because both the data disk and the parity disk reads and writes simultaneously.

I though that unRAID would fist move the data from the cache drive to the data disk then run the parity check. Or does it do both at the same time?

 

Is this normal?

 

[JorgeB]

8 minutes ago, queueiz said:

Or does it do both at the same time?

 

Parity in unRAID is always updated in real-time.

[queueiz]

2 minutes ago, johnnie.black said:

 

Parity in unRAID is always updated in real-time.

 

 

Okey so this is why it's reading and writing at the same time. This is kinda bad for performance, hence that's why we use cache drives i guess.

Is there a way to pause the parity check or temporary disable it?

 

[JorgeB]

3 minutes ago, queueiz said:

Is there a way to pause the parity check or temporary disable it?

 

Not temporarily, there is a faster writing mode called reconstruct write, aka turbo write, at the expense of all disks spinning up for writes, see below for how each mode works: