I bought 3 WD Green 1TB drives and want to upgrade some of the drives in my server.  I took out the old parity drive and popped in the new drive and just finished rebuilding the parity.  So far so good.  However, I now want to use the old parity drive to replace one of my existing smaller drives.  Do I need to first format the old parity drive or can I just pop it in place of the older drive?  Will I be prompted to rebuild the drive?  Not sure how that actually works since I've never actually rebuilt a drive before.  Any assistance is appreciated!

If you shut down the server, unplug the smaller disk and then hook up the old parity drive to exactly the same port, and then reboot, unRAID should boot and indicate that when you start the array it will begin rebuilding the data disk.  No need to format or anything.

Cool, thanks!  It's a pain replacing disks.  Shut down, remove drive, pop in new one, rebuild.  Then do it all again...and again lol

Just remember to always press "Start" to reconstruct the contents of the smaller drive onto the larger one installed in its place.

 

DO NOT PRESS THE BUTTON LABELED AS "restore" as it invalidates parity, and it will not reconstruct anything.  (you'll still have the data on the smaller drive you removed, but it will be painful getting to it)

So far so good.  One drive done.  I checked it to make sure the data was there.  It was, so now on to the next drive.

I was going to post the following, but now I'm having second thoughts about the usefulness of it since the 'rebuild' process reads all disks as well (just not all sectors of all disks).  Fellow hero members...is the following true?

 

I recommend running a parity check immediately after each drive rebuild.  Yes, this more or less doubles the amount of time that it takes to do a multi-drive upgrade as you are doing.  However, it ensures that all your parity information is readable.  This is not an essential step, just a recommendation.

I was going to post the following, but now I'm having second thoughts about the usefulness of it since the 'rebuild' process reads all disks as well (just not all sectors of all disks).  Fellow hero members...is the following true?

 

I recommend running a parity check immediately after each drive rebuild.  Yes, this more or less doubles the amount of time that it takes to do a multi-drive upgrade as you are doing.  However, it ensures that all your parity information is readable.  This is not an essential step, just a recommendation.

If you have doubts of your hardware, use the following command to initiate a read-only parity check.

(the NOCORRECT argument must be in all capital letters)

 

/root/mdcmd check NOCORRECT

 

It will look like the normal parity check from the web-interface, and, in fact, it might even say it is correcting, but it is not.

 

The NOCORRECT feature is only available on more recent versions of unRAID.  (Since 4.5-beta2 released in March 2009)

See here:  http://lime-technology.com/forum/index.php?topic=3430.msg29619#msg29619

 

Joe L.

I was going to post the following, but now I'm having second thoughts about the usefulness of it since the 'rebuild' process reads all disks as well (just not all sectors of all disks).  Fellow hero members...is the following true?

 

I recommend running a parity check immediately after each drive rebuild.  Yes, this more or less doubles the amount of time that it takes to do a multi-drive upgrade as you are doing.  However, it ensures that all your parity information is readable.  This is not an essential step, just a recommendation.

 

Agree with everything except the last sentence.  (It IS an essential step.)

I was going to post the following, but now I'm having second thoughts about the usefulness of it since the 'rebuild' process reads all disks as well (just not all sectors of all disks).  Fellow hero members...is the following true?

 

I recommend running a parity check immediately after each drive rebuild.  Yes, this more or less doubles the amount of time that it takes to do a multi-drive upgrade as you are doing.  However, it ensures that all your parity information is readable.  This is not an essential step, just a recommendation.

 

Actually, I did this.  I felt it was better to be safe than sorry.

I was going to post the following, but now I'm having second thoughts about the usefulness of it since the 'rebuild' process reads all disks as well (just not all sectors of all disks).  Fellow hero members...is the following true?

 

I recommend running a parity check immediately after each drive rebuild.  Yes, this more or less doubles the amount of time that it takes to do a multi-drive upgrade as you are doing.  However, it ensures that all your parity information is readable.  This is not an essential step, just a recommendation.

No, it is NOT true.  It does not read the disk being rebuilt.  You have no way to know if what you've written is correct unless you perform a parity check which then reads what you've just written during the rebuild.

 

The NOCORRECT parity check is better in this situation since it will not clobber parity if by some chance what you rebuilt was written incorrectly to the disk being rebuilt.  Otherwise, if (worse case, all garbage was written to the disk even though it appeared to be written properly ) you perform a normal parity check the garbage would be considered the "correct" data and the parity data used for the rebuild overwritten to correspond. (wiping away any chance of a second rebuild onto a second replacement drive)