What's the difference between a "Read check" and a "Parity check"?

[cybersteel8]

I have migrated all my data to my new array, and I am yet to add parity. I am considering running a "Read check" on my array before adding the parity.

 

Is there any value in this? I understand that once I have my parity drives installed, a "Parity check" will be checking the data against the parity data, but without parity, does a "Read check" do anything? I am specifically referring to the button at the bottom of the Main page, where you can also see options like Reboot/Shutdown/Clear Stats and the Start/Stop array buttons etc.

 

So, is there a difference between a Parity Check and a Read Check? Without parity, does a Read Check do anything useful?

 

Thanks for your information. I couldn't find anything in the manual regarding this, unfortunately.

[JorgeB]

Read check like the name implies only reads the data disks, it will report any read errors.

[cybersteel8]

11 hours ago, JorgeB said:

Read check like the name implies only reads the data disks, it will report any read errors.

Ah, so it functions kind of like a health check of the drive to see if all the sectors are still readable?

Thanks!

[JorgeB]

12 hours ago, cybersteel8 said:

so it functions kind of like a health check of the drive to see if all the sectors are still readable?

Yep.

[cybersteel8]

Thanks, that's very helpful.

I have a follow-up question:

I see that Unraid has a Parity Check Scheduler built-in but there isn't one for a Read Check.
Is it safe to assume that when a Parity Check runs, it is also implicitly doing a read check at the same time?

[JorgeB]

Yes, it also reads all the disks during a parity check.