Hello everyone.

I'm reading through this guide here: https://wiki.unraid.net/The_parity_swap_procedure and I'm a little uncertain about the steps I need to take.

 

I want to replace the current 8TB parity drive with the unassigned 12tb drive (sdf) below.  After the swap and parity has been rebuilt on to the new 12tb drive I want to take the 8tb drive (former parity drive) and add it as a data drive in the array. Current parity drive is healthy, zero errors on full parity scan/check yesterday.  Preclear on the 12tb (sdf) drive is about 50% complete.

 

In the guide it talks about powering down, removing data drives, unassigning etc and I'm a little unclear what steps apply to my setup / use case here.  As mentioned, the new 12tb drive is already on and installed.  Parity drive is healthy.

 

Can someone provide simple step-by step info here that apply to my setup? Never done this before and I _really_ do not want to screw up my array in the process.  If i have an issue during rebuilding parity (on the 12tb (sdf) drive) can i fall back to the current 8tb drive? If i have an issue during rebuilding parity (on the 12tb (sdf) drive) can i fall back to the current 8tb drive?

 

 

 

Edited April 9, 20206 yr by repomanz
added another question

Not going to comment on the Parity Swap Procedure, as I've never done it and it's just a "shortcut" for the standard way

 

Stop the array 

Assign the 12TB as parity drive

Start the Array and let it build the parity drive

 

After that's done, stop the array and add the original 8TB as a data drive 5.  Unraid will clear it in the background and when that's done (hours), then the storage space is available.

 

The standard way does give you a fall back, as the original parity drive is available for you to reinstall if something terrible goes wrong.

11 minutes ago, Squid said:

Stop the array 

Assign the 12TB as parity drive

Start the Array and let it build the parity drive

before starting this above, I would need to power down, disconnect power from current 8tb parity drive. power up and then add the 12tb drive as parity?

Edited April 9, 20206 yr by repomanz
clarification

Safest way

Squid is correct but you can also stop the array, unassign the 8TB parity disk, assign the 12TB disk to parity, and assign the 8TB disk to the next data disk slot all in one step.  This is a supported operation.

Parity swap isn't exactly a shortcut for the standard way. It really is intended for the situation where you need to replace a data disk, but you don't want to be forced to buy a disk as small as parity. It allows you to copy parity to a larger disk, then replace the data disk with the old parity and rebuild it. So it lets you get a new larger parity disk instead of making you buy a disk as small as the original parity to replace the data disk.

 

Since you aren't replacing any disks, it doesn't apply at all.

 

And since you will be rebuilding parity anyway, might as well rebuild it with the added data (former parity) disk already in place. As noted by jonp.

6 hours ago, jonp said:

you can also stop the array, unassign the 8TB parity disk, assign the 12TB disk to parity, and assign the 8TB disk to the next data disk slot all in one step.  This is a supported operation.

Are you sure about that? Pretty sure that won't work and you'll get this unhelpful error.

I guess New Config would have to be done then, but if you're rebuilding parity anyway might as well get the added disk as part of that parity build instead of waiting for it to clear. Since it's been a couple of days now probably something has already been done.

20 hours ago, johnnie.black said:

Are you sure about that? Pretty sure that won't work and you'll get this unhelpful error.

yup - i couldn't change the parity to 12tb and put the former 8tb parity drive in the array at the same time.  Got disk error so rebuilding parity on the 12tb while the former parity drive is sitting unassigned.

Since you didn't

On 4/11/2020 at 8:34 AM, trurl said:

New Config would have to be done then, but if you're rebuilding parity anyway might as well get the added disk as part of that parity build

you will have to add it after parity build and

On 4/11/2020 at 8:34 AM, trurl said:

waiting for it to clear

 

 

I find the guides pretty confusing. I want to replace my parity drive with a larger one on the same SATA port. Then add the old parity drive as a data drive on a different SATA port. This is because I have bought a MZHOU PCIe SATA Card 6 Port to add extra drives, and I feel like it's safer to have the parity drive on a mainboard SATA port (or is that nonsense..?).

 

I wanted to do it like this:

 

1. Stop array and power down system

2. Remove old parity drive

3. Install new drive on the same SATA port as the old parity drive

4. Boot system

5. Assign new drive as parity

6. Start array and let it rebuild parity

7. Stop the array

8. Power down system

9. Add old parity drive to a MZHOU SATA port

10. Boot system and assign old parity drive as a data drive

11. Start array

12. DONE!

 

That should work right? This seems like the simplest way to me, or am I missing something?

 

Thanks in advance.

 

Edit: also, if anyone knows, that MZHOU card has no drive size limit, does it? I want to use 14TB+ drives with it.

Edit2: this edit comes very late, but just in case other people come across this post: that MZHOU card did not work in my system. I am not sure if it was a faulty card or if it simply doesn't work with Unraid. I sent it back for a refund.

Edited September 4, 20232 yr by Aemstel

4 hours ago, Aemstel said:

That should work right?

Yes.

3 hours ago, JorgeB said:

Yes.

 

Great, I was hoping for a short answer like this

Thanks! Will go ahead with it.

 

On 10/3/2022 at 10:11 PM, Aemstel said:

1. Stop array and power down system

2. Remove old parity drive

3. Install new drive on the same SATA port as the old parity drive

4. Boot system

5. Assign new drive as parity

6. Start array and let it rebuild parity

7. Stop the array

8. Power down system

9. Add old parity drive to a MZHOU SATA port

10. Boot system and assign old parity drive as a data drive

11. Start array

12. DONE!

 

@JorgeB@Squid - So I just upgraded the drives in my backup NAS and want to use them in my Unraid server as they are larger than the existing drives.  Since these drives contain data, is there anything I need to do after #5 in my situation?

9 hours ago, rockbox948 said:

Since these drives contain data, is there anything I need to do after #5 in my situation?

No, but of course any data on those drives will be deleted.

33 minutes ago, JorgeB said:

No, but of course any data on those drives will be deleted.

If you do not want the data to be deleted and the drives added as additional drives then you need to go via Tools->New Config to add them.  The New Config tool leaves drives previously used on an Unraid system with their data intact.    You then need to build new parity to match the new drive set.

@JorgeB Thanks.  I just wanted to make sure I didn't need to reformat the drive first before letting Unraid recreate it as a parity drive.

 

Is the same true for taking one of the old NAS drives with data on it and bringing it over to replace one of the existing Unraid drives?  Unraid will take care of deleting all of the existing data on the old NAS drive on its own?

2 minutes ago, itimpi said:

If you do not want the data to be deleted and the drives added as additional drives then you need to go via Tools->New Config to add them.  The New Config tool leaves drives previously used on an Unraid system with their data intact.    You then need to build new parity to match the new drive set.

@itimpi  Thanks!  I didn't know this was a possibility.  I may do that in a future situation.

Edited December 5, 20223 yr by rockbox948

Just now, rockbox948 said:

@JorgeB Thanks.  I just wanted to make sure I didn't need to reformat the drive first before letting Unraid recreate it as a parity drive.

 

Is the same true for taking one of the old NAS drives with data on it and bringing it over to replace one of the existing Unraid drives?  Unraid will take care of deleting all of the existing data on the old NAS drive on its own?

If you add simply add a drive (parity or data) to an existing parity protected array then the existing contents are irrelevant as Unraid will overwrite them.

7 minutes ago, itimpi said:

If you add simply add a drive (parity or data) to an existing parity protected array then the existing contents are irrelevant as Unraid will overwrite them.

@itimpi Thanks for your help!

I'm jumping in on this topic as I'm in the middle of the same process but taking a different approach.  I didn't want to remove my one parity drive and then rebuild a new parity drive as that would put my array at risk. I followed this process, please tell me if there is a problem.

 

I currently have 1 4 TB parity drive and my array is filling up. I leveraged the black Friday deals and bought two 20 TB drives and have an extra 14 TB drive as well. I added the 14 TB drive to the data array and one 20 TB drive as "Parity 2". My plan is to restart the system and let Parity 2 build parity.  Once that is done, I will add the 2nd spare 20 TB drive to the data array (now that I have a 20 TB Parity 2 drive) and move the 14 TB drive that was formerly Parity 1 to the data array.  Restart the system and the array will come back on line with 1 parity drive in the Parity 2 position.

 

Any issues with that approach?  Thanks for the help!!

1 hour ago, smoothvirus said:

currently have 1 4 TB parity drive

This confused me at first. You mean you have a 14TB parity drive, not one 4 TB parity drive.

 

1 hour ago, smoothvirus said:

Restart the system and the array will come back on line with 1 parity drive in the Parity 2 position.

So you won't have a drive assigned as parity (P), only a drive assigned as parity2 (Q)? Certainly that is allowed. I am wondering though about the size and number of your data disks and whether you should consider dual parity instead.

 

 

I did a little more research and discovered that the computations for Parity 1 and Parity 2 are different and that you can't have a Parity 1 without a Parity 2.  I bit the bullet and just replaced my Parity 1 drive drive with the larger 20 TB drive. Fortunately no errors but it was a fun day  (26 hours) to run unprotected as the Parity 1 drive rebuilt itself.

1 minute ago, smoothvirus said:

I did a little more research and discovered that the computations for Parity 1 and Parity 2 are different and that you can't have a Parity 1 without a Parity 2.

Not sure what you are trying to say?   You can have parity1 and/or parity2.   The only requirement is that no data drive can be larger than the smallest parity drive if you have 2 parity drives.

22 minutes ago, smoothvirus said:

you can't have a Parity 1 without a Parity 2

 

As I already said

On 12/19/2022 at 3:47 PM, trurl said:

Certainly that is allowed