All of your options look viable so it will be a time/risk tradeoff.

 

If you can afford the array downtime it would probably be quickest to assign both 18TB drives to parity1 and parity2 and build them in parallel while in Maintenance mode.     I mentioned maintenance mode to ensure no array updates happen while building the new parity which means the old 14TB parity remains valid.  While this is going on keep the old parity1 intact just in case an array drive has problems as this gives a fall-back path.   On completing the move to 2 x 18TB parity drives the old 14TB parity drive can now be assigned as a data drive.

 

If you cannot afford the time in maintenance mode then your third option looks safest as you would have a valid parity drive throughout.

 

An option you have not mentioned which is the quickest is to use the Tools->New Config to allow you to assign both 18TB drives as parity and the 14TB drive as a new data drive and then build the new parity based on the new drive configuration.  The downside of this is that a failure of a data drive before the new parity is built could lead to data loss.  

 

Note that Unraid will not allow you to combine making changes to parity drives and adding data drives at the same time if you have not gone the New Config route.

 

8 minutes ago, itimpi said:

All of your options look viable so it will be a time/risk tradeoff.

 

If you can afford the array downtime it would probably be quickest to assign both 18TB drives to parity1 and parity2 and build them in parallel while in Maintenance mode.     I mentioned maintenance mode to ensure no array updates happen while building the new parity which means the old 14TB parity remains valid.  While this is going on keep the old parity1 intact just in case an array drive has problems as this gives a fall-back path.   On completing the move to 2 x 18TB parity drives the old 14TB parity drive can now be assigned as a data drive.

 

If you cannot afford the time in maintenance mode then your third option looks safest as you would have a valid parity drive throughout.

 

An option you have not mentioned which is the quickest is to use the Tools->New Config to allow you to assign both 18TB drives as parity and the 14TB drive as a new data drive and then build the new parity based on the new drive configuration.  The downside of this is that a failure of a data drive before the new parity is built could lead to data loss.  

 

Note that Unraid will not allow you to combine making changes to parity drives and adding data drives at the same time if you have not gone the New Config route.

 

 

Thank you for the fast feedback!

Just to clarify, going your first suggested route (maintenance mode) takes everything offline. But doing the other option - adding one drive to make it parity 2, then replacing the smaller parity drive - would allow the server to continue to function as normal? Or should I still stop my docker containers throughout that process (ie could Plex continue to run while parity 2 builds, then while parity 1 is built on the new parity 1 drive (since parity 2 is now valid)?

5 minutes ago, Ollie said:

But doing the other option - adding one drive to make it parity 2, then replacing the smaller parity drive - would allow the server to continue to function as normal?

 

It would continue to function as normal, although performance might be degraded if there is much other disk activity at the same time due to drive contention.  If there is only light disk activity then it may be more convenient to leave everything available running as normal.

Just went through the process (replacing smaller parity drive with larger parity drive, and then moving the old parity drive to data), and it was confusing and didn't go the way I wanted.  I wanted the safest and easiest option. 

 

What I have right now is a full/clean parity sync, while the old parity is sitting unassigned.  However, my array is online, so the old parity is obsolete.  This doesn't sound like the safest, nor the easiest option.

 

I thought I could do a parity copy.  I thought Unraid would have something built-in to copy the parity bits from the smaller drive to the larger drive.

 

If parity copy is not possible, then Unraid could do both Parity 1 and Parity 2.  Then when Parity 2 is complete, remove Parity 1 and move drive to data; Parity 2 drive now becomes the Parity 1 drive.

 

In the future I hope Unraid has scenario buttons that walk the user through the process for common different scenarios.

 

 

 

 

 

23 minutes ago, Jaybau said:

Then when Parity 2 is complete, remove Parity 1 and move drive to data; Parity 2 drive now becomes the Parity 1 drive.

That's not possible since parity2 is calculated in a different way, they are not interchangeble, but you can add parity2, remove parity1 and use only parity2.

resurrecting this thread for a similar question. I read the legacy parity swap guide and this thread, but want to double check before starting anything.

 

I want to begin replacing smaller capacity drives with larger, one by one. My box is totally full with all sata ports populated: 10 slots: 2x SSD cache. 8x hard disks - 6 data plus P1 and P2 - every single hard disk is the same capacity. (I'm safe to ignore my two SSD cache disks in this exercise, yes?)

 

I can operate in Maintenance Mode. Everyone can deal with Unraid server being offline for a while.

 

I am running unraid v6.11.5 - this is last version before the major change in v6.12 which I was afraid to upgrade to since everything works as I like it. but if I should upgrade before I start anything, please do let me know!

 

What I gather I should do is:

1. Stop all my dockers etc and stop array.

2. Pick a data drive and unassign it. 

3. Start array checkboxing that I really want to do this. (Not sure what happens other than it'll show Unassigned after it restarts?)

4. Stop array. Power down. Pull out that drive. Plug in the new bigger drive.

5. Power on. (docs say unraid v6+ doesn't need me to Preclear the drive if it's going to become a Parity drive anyway. true?)

6. As array is still stopped, unassign P1 and assign the newly plugged in drive to become the new P1. Then assign the old P1 as a data drive.

7. Continuing with the guide, goto Main->Array Ops, copy parity over, and wait for it to do its thing.

8. When it's done, I should get option to Start array and it'll tell me that it's got to rebuild old P1 into data drive. Wait for it to do its thing. 

 

edit: Only need this when drive is bad. If healthy, just pull P1 and plug in bigger new drive and let unraid rebuild parity. then repeat with P2.

 

Now, do I repeat this whole procedure for P2? (ie, pick a diff data drive, unassign, pull it, plug in new bigger drive, etc) Or is there a faster way to get new P2 done?

 

And when this is all done, when I start replacing my data drives with larger capacity ones, I just follow the replace data drive guide which seems pretty straightforward?

 

Thanks

Edited May 10, 20251 yr by darckhart
clarified

You don't need to use the parity swap if all disks are OK and enabled, just upgrade the parity drives first, and when the sync is done, start replacing the array disks.

oh wow that's easier! I was thinking I was going to mess something up with all the swapping around haha. OK cool!

I've in the same situation, and just submitted a feature request to allow a straightforward, efficient, and safe procedure for upgrading the parity drive. Add your thoughts in the FR thread on whether you think it'd be useful, and how you'd change it.

Apologies for yet another resurrection. About to do this and wanted to check my understanding before I do.

I have 2 new 10TB drives to replace my parity (currently 4TB) and a 3TB data drive. I have 3 data drives, and all available SATA slots are filled.

My understanding is that my safest approach is as follows:

1) Stop the array

2) Unallocate the parity disk

3) Power down and physically swap out the existing parity with the new disk

4) Reboot

5) Allocate the new disk as parity

6) Start the array and let it rebuild the parity on the new drive

7) Once complete follow the process for data drive replacement

That would work.

Keep the old parity intact until the rebuild of the new parity completes just in case a data drive fails while building new parity as that gives a recovery option. Ideally rebuild the new parity in maintenance mode as that would stop any writes being made to a data drive until the parity rebuild completes.

Thanks so much

EDIT: My array will not start, I tried new config with all allocations preserved and it the array still won't start

Any suggestions?

Edited January 25Jan 25 by be4con

42 minutes ago, be4con said:

My array will not start,

What error do you see? Post a screenshot showing that and also the diagnostics

Just now, JorgeB said:

What error do you see? Post a screenshot showing that and also the diagnostics

Ah, you can tell I'm not a power user... I was trying to start the array from the Dashboard, but received no error message. When I try to start it from the Main page, I get the error "Wrong Pool State cache - too many wrong or missing devices"

Under Pool it shows as 'unassigned', there is no option in the drop-down to assign.

tower-diagnostics-20260125-1228.zip

Just now, be4con said:

Under Pool it shows as 'unassigned', there is no option in the drop-down to assign.

If the pool doesn't have any devices, click on it and then "remove pool", you cannot start the array with an empty pool.

1 minute ago, JorgeB said:

If the pool doesn't have any devices, click on it and then "remove pool", you cannot start the array with an empty pool.

Bingo! That was so simple, thank you!

Hi,

I've read this whole thread but since it's going back and forth between 1 and 2 parity drives I wanted to test my specific setup and use case.

I've 14 drives, 1 parity with a mix of different sizes. Parity drive is 20TB and I've bought two 28TB, one I'm gonna have to replace parity drive with and the second will be on the shelf as a spare drive. I've one slot left to add a drive, my plan therefore is to add one 28TB, switch current parity drive to 28TB and then expand the array with the 15th drive (old parity 20TB) and rebuild/expand at the same time.

Something tells me this is very bad practice, or wont even work but I'm hoping I can kill two birds with one stone. Is it possible to expand and rebuild parity at the same time? Since I've big drives, the rebuild will take a long time so if I can do those two tasks concurrently, I'd be very happy. I know about the risks, and having only single parity is not best practice - I know. But all content can be re-fetched so I'm OK to live with the risk. The only thing I want to avoid is executing my plan only to realize I've erased everything knowingly/by mistake.

Thanks

You cannot both swap parity for a larger drive and also add a new drive in the same step and remain protected against data loss. If data loss is a criteria it needs to be done in two steps.

Having said that if you do not mind running unprotected for a time then you could use Tools->New config (starting with the retain all option) and then assign a 28TB drive to parity and then assign the old parity drive to a new slot. When you start the array Unraid will start to build new parity on the 28TB drive and the old parity drive will show up as unformatted and will need formatting before it can be used to store data. You can even do this format while parity is rebuilding as although it will slightly slow down the rebuild while it is running it does not take very long. The downside of this approach is that if an existing data drive fails before parity completes rebuilding its contents will be lost but that may not be critical to you?

Thank you for the quick reply!

Losing a data drive during parity rebuild is a risk I'm willing to take. Your instructions sounds like I'm able to do exactly what I want, with the risk of losing data of course if a data drive should fail, but the process itself wont delete any existing data if I understand you correctly? Except for the new data drive and old parity drive which is by design and something I'm fully aware of.

20 minutes ago, pest0n said:

Thank you for the quick reply!

Losing a data drive during parity rebuild is a risk I'm willing to take. Your instructions sounds like I'm able to do exactly what I want, with the risk of losing data of course if a data drive should fail, but the process itself wont delete any existing data if I understand you correctly? Except for the new data drive and old parity drive which is by design and something I'm fully aware of.

Yes - when you use the New Config tool then any drives previously used by Unraid keep their content intact.