I'm going to be replacing my parity disk with a 4TB in the next few days after some pre-clearing.

When I remove the old parity 2TB disk and use again it shouldn't need pre-clearing because it's already proved itself for the last 3 years.

 

When I want to expand the array with the old parity disk as a data drive do I just select it in the GUI, format and then start using the larger array?

Am I missing something, after all the disk did have the parity info on it, does the re-format take care of all that?

In order to add a disk to an array with parity, it will have to be cleared so it will match parity. If you don't preclear it, unRAID will do so before it will let you format it. Letting unRAID clear it will take less time than doing a "default" preclear but your array will be offline until it finishes.

 

I have never used them, but there are some options to the preclear script that will let you skip some of the steps, so you could do that instead and save some time doing a preclear. Just run the preclear script without specifying a drive and it will display the help. I just did this and it looks like -W will skip pre-read and -n will skip pre-read and post-read. Whatever you do though, you will have to let it write zeroes to the entire drive and then write the "clear" signature so unRAID will know that it doesn't need to be cleared.

 

Okay thanks!

 

I don't mind running a full pre-clear on it. I've been messing about with data rebuilds and parity syncs for the last 4 days now with 3 more days of pre-clearing the new parity drive before it gets swapped, 1 more day won't hurt.

 

 

The old parity drive has had plenty of use, so any necessary sector reallocations have undoubtedly already been done.  If you just do a preclear with the -n parameter it will only do the actual clear ... skipping both the pre-read and post-read steps => this will take about 1/4th the time of a full pre-clear cycle -- and is all you really need to do for that disk.

 

Thanks

 

So rather than this:

cd /boot
./preclear_disk.sh -A /dev/sda

 

It would be this?:

cd /boot
./preclear_disk.sh -n /dev/sda

Thanks

 

So rather than this:

cd /boot
./preclear_disk.sh -A /dev/sda

 

It would be this?:

cd /boot
./preclear_disk.sh -n /dev/sda

 

You can still include the -A if you'd like (not needed if your default partition alignment is 4k aligned in the Disk settings (on the Settings tab in the Web GUI)

 

But yes, the -n parameter will do as I noted -- just the actual clear ... and this takes MUCH less time than a full pre-clear cycle (roughly 1/4th of the total time)

 

If you want to include the -A, the command would be:

 

./preclear_disk.sh -n -A  /dev/sda[/code]

Wait wait wait.

 

If you are replacing parity, there is absolutely no need to preclear the old parity. In fact, it prevents you from recovering should a drive fail in the middle of the parity build.

 

What you should do, maybe you already have, it run a parity check before beginning. Check smart reports on all drives (if you are using myMain you can see all of the smart reports on one screen). If you see signs of a failing disk, do not proceed.

 

Stop the array, take a screenshot of the array configuration.

 

Run initiconfig.

 

Re-assign all of the drives to their slots (older unRAID versions didn't require you do this but ever since the separate devices tab was removed you do), except assign your new drive as parity and your old parity drive to the next drive slot. Make 110% sure you do not assign a data disk to the parity slot!!

 

Double check everything.

 

Start the array. Parity build will begin to include your old parity drive. The array will be usable. The old parity disk will show as unformatted (for recoverability you could wait to format it until the new parity is built before reformatting it and use it to recover if a disk died in the middle of the parity build. It would be complex but possible if you do not do ANY writes to any disk on the array during the parity build).

 

No harm doing what others have requested, but this is less painful and a little safer.

I'd do it a bit differently.  I agree you do NOT want to modify the old parity before you've got a good parity sync on the new drive.

 

But I'd keep it entirely out of the array until that was done.

 

e.g.  Remove old parity; assign new parity.  Wait for parity sync.  Do a confirming parity check to ensure all went well.    NOW do a preclear with -n on the old parity drive;  then assign it to a data slot; and you're ready to go 

The old parity drive won't be in the unRAID server while I get the new parity up and running. I get overly concerned with drive assignment letters and stuff because I don't want to mix anything up.

 

Hell I might even get it taken on a road trip so I can't get them mixed up in anyway.

 

When the new parity is synced and checked then I will allow the old one back in the house. 

Wait wait wait.

 

If you are replacing parity, there is absolutely no need to preclear the old parity. In fact, it prevents you from recovering should a drive fail in the middle of the parity build.

 

What you should do, maybe you already have, it run a parity check before beginning. Check smart reports on all drives (if you are using myMain you can see all of the smart reports on one screen). If you see signs of a failing disk, do not proceed.

 

Stop the array, take a screenshot of the array configuration.

 

Run initiconfig.

 

Re-assign all of the drives to their slots (older unRAID versions didn't require you do this but ever since the separate devices tab was removed you do), except assign your new drive as parity and your old parity drive to the next drive slot. Make 110% sure you do not assign a data disk to the parity slot!!

 

Double check everything.

 

Start the array. Parity build will begin to include your old parity drive. The array will be usable. The old parity disk will show as unformatted (for recoverability you could wait to format it until the new parity is built before reformatting it and use it to recover if a disk died in the middle of the parity build. It would be complex but possible if you do not do ANY writes to any disk on the array during the parity build).

 

No harm doing what others have requested, but this is less painful and a little safer.

 

Thanks bjp999.

 

I have the same question as the OP. I have replaced the old 3TB parity drive (currently sitting out of the tower - physically removed) with a new 5TB one and parity sync is currently running.

 

I did not do a parity swap since I did not want to use the parity disk to replace an existing array drive, but instead to expand the array. I plan to add the old disk to the array after the parity sync is complete and I have confirmed parity is valid with a parity check.

 

So from your reply above I understand that I don't have to do a parity check on the old 3TB parity drive before adding it to the array - stop the array, assign the old 3TB parity drive drive to a vacant slot and start the array - is that correct?

I have the same question as the OP. I have replaced the old 3TB parity drive (currently sitting out of the tower - physically removed) with a new 5TB one and parity sync is currently running.

 

I did not do a parity swap since I did not want to use the parity disk to replace an existing array drive, but instead to expand the array. I plan to add the old disk to the array after the parity sync is complete and I have confirmed parity is valid with a parity check.

 

So from your reply above I understand that I don't have to do a parity check on the old 3TB parity drive before adding it to the array - stop the array, assign the old 3TB parity drive drive to a vacant slot and start the array - is that correct?

Since you are building parity without the old parity drive in the array, it will have to be cleared so parity will remain valid. If you don't preclear it unRAID will take your array offline while it clears it. Note that the method bjp999 outlined built parity with the old parity drive already assigned as a data disk so the parity sync included it, but that is not what you have done.

I have the same question as the OP. I have replaced the old 3TB parity drive (currently sitting out of the tower - physically removed) with a new 5TB one and parity sync is currently running.

 

I did not do a parity swap since I did not want to use the parity disk to replace an existing array drive, but instead to expand the array. I plan to add the old disk to the array after the parity sync is complete and I have confirmed parity is valid with a parity check.

 

So from your reply above I understand that I don't have to do a parity check on the old 3TB parity drive before adding it to the array - stop the array, assign the old 3TB parity drive drive to a vacant slot and start the array - is that correct?

Since you are building parity without the old parity drive in the array, it will have to be cleared so parity will remain valid. If you don't preclear it unRAID will take your array offline while it clears it. Note that the method bjp999 outlined built parity with the old parity drive already assigned as a data disk so the parity sync included it, but that is not what you have done.

 

Thank You!  Got it! Will do a preclear on the parity after I am done with the parity sync and parity check on the new parity drive. Appreciate the quick response.