Hope this is easy: After installing a new parity drive last night, I moved the old parity drive to an array position. In the Simple Features version of the WebGUI, I assigned the next position to the former parity disk. The system terminal message I got showed that preclear had begun.

 

It had counted up to about 2% when I had to shut down my web browser for another reason. Now, when I try to use "tower/main" as a URL, my browser can't find it. I can, however load unMENU, which reports that the array is stopped and that parity is not valid: disk new. This what I would expect. The last line in the syslog indicates that preclear has been started. And when I refresh the unMENU Main page the writes for that disk shows to be counting up. That tells me that the preclear is proceeding.

 

But I can't seem to restart the main webGUI. Even when I click on "unRAID Main" in unMENU, the browser times out and reports a time-out error. Is this normal? Should it be?

 

My gut feeling is that emhttp invoked the preclear, and while that preclear process is underway, it goes deaf.

 

Rick "really just curious" Denney

emhttp is clearing the data drive. This is a known defect and the reason the pre-clear.sh was developed.

emhttp is clearing the data drive. This is a known defect and the reason the pre-clear.sh was developed.

 

Is that the only fault, or does pre-clear.sh do something else, too?

 

Rick "who can live with this if it's a known issue" Denney

the other advantage of the preclear-script is, to keep the down time of your array to a minimum. if unraid has to clear the drive itself, you can't access your data for several hours. but if you add a precleared drive, you can directly start the array again and access your data.

 

(also, preclearing works as a burn-in test, showing, if there is anything wrong with the disk...)

Is that the only fault, or does pre-clear.sh do something else, too?

 

Rick "who can live with this if it's a known issue" Denney

As long as the drive you are adding is perfect, the stock clearing routine is ok, as long as you don't mind the wait. The other issue preclear addresses is if the drive has doesn't return a zero after it's written. The stock clear function makes no effort to verify if the drive has indeed retained the zero data, where preclear writes and verifies the drive. Several passes of the preclear script are recommended to weed out drives that fail early in their life. A not insignificant number of brand new drives have a bad habit of failing soon after they are put in service.