Hello everyone,

 

I'm new in Unraid OS, and have installed it on NAS Link Station N1.

As i read across the internet, i made this summary: (correct me if i'm wrong)

 

1. Unraid is not functionating like standard RAID (for me needed RAID 1).

• RAID made full copy of the data on both disks, and if one disk has malfunctionated, i can replace the disk, the controller copy the data itself, rebuild RAID, or just attach the fully functional disk on PC and access the data.
• Unraid write data on one disk, and on the other he made parity write of data, and if one disk has malfunctionated, when the bad disk is replaced, it rebuilds from parity disks. If i attach the parity disk to PC it will be unusable, and it does not have actual copy of the data on the parity disk.

 

2. I can use 1 parity disk and many data disk, just to be sure that the size od parity disk is not smaller of the sum on the data disks. For example, if it has 4x1TB data disks, the parity disk must be at least 4tb.

 

Now to get on the real scenario.

I have mount 4x1TB NVMe SSD, and 2x128GB SATA 2.5" SSD.

Setup is made to use 2x1TB NVMe SSD for DATA, and 2x1TB NVMe SSD for Parity.

2x128GB SATA 2.5" SSD were also setup for DATA.

 

I start the array, made all settings in Unraid for my needs, installed many docker containers, setup share folders and so on. Everything was just fine.

No errors, no warnings, Parity check it sais it's OK.

After a while i decide that the two SATA SSD are not necessary for me and choose to remove them.

I made on this way, stopped the array, removed the SSD from Array, shutdown the system, removed physically the drives, start the system.

 

When it started became the warning about shared folders "Some or ALL files are unprotected" which i don't know what it means.

I made another Parity check, and everything is OK, but this warning stays. 

Also i noticed that the partition of the two removed disks, are still shown in the array list. Don't know also why.

 

 

 

Can someone try to explain what is going on, and what is the solution to made this system to work without warnings.

 

Thanks in advance.

Edited March 22, 20251 yr by steff_92

Parity must be at least as large as the largest single data disk.

 

https://docs.unraid.net/unraid-os/overview/nas/#parity-protected-array

 

SSDs in the parity array cannot be trimmed.

 

Sounds like what you want are multidisk pools not part of the array. These support various forms of redundancy with btrfs or zfs.

 

And Unraid V7 does not require an array. 

Quote

 

Parity must be at least as large as the largest single data disk.

 

I fulfill this requirement.

Have x2 parity by 1TB.

 

For the trim i'm aware, and shutdown the auto schedule triming process.

 

Now in the moment i have returned the x2 2.5" SSD which were removed before, and after start on the array it has started itself with Data Rebuild, but on those disks there was nothing. They were empty.

 

 

I want to use 2x1TB for DATA and 2x1TB for Parity in case of any one drive failure.

Is it this scenario OK?

I try this method and sucessfully removed the 2 devices.

The parity disk were renewed from scratch.

 

Quote

 

Removing data disk(s)

Removing a disk from the array is possible, but normally requires you to once again sync your parity disk(s) after doing so. This means that until the parity sync completes, the array is vulnerable to data loss should any disk in the array fail.

To remove a disk from your array, perform the following steps:

Stop the array

(optional) Make note if your disk assignments under the main tab (for both the array and cache; some find it helpful to take a screenshot)

Perform the Reset the array configuration procedure. When doing this it is a good idea to use the option to preserve all current assignments to avoid you having to re-enter them (and possibly make a mistake doing so).

Make sure all your previously assigned disks are there and set the drive you want removed to be Unassigned

Start the array without checking the 'Parity is valid' box.

A parity-sync will occur if at least one parity disk is assigned and until that operation completes, the array is vulnerable to data loss should a disk failure occur.

 

 

I want to use 2x1TB for DATA and 2x1TB for Parity in case of any one drive failure.

Is it this scenario OK, still active question?

3 hours ago, trurl said:

Parity must be at least as large as the largest single data disk.

The reason I said this is because you seemed to think parity had to be as large as the total data capacity of the array.

4 hours ago, steff_92 said:

size od parity disk is not smaller of the sum on the data disks

For example, you could have 1TB parity and lots of data disks totalling many TB, as long as none of them were larger than that 1TB parity.

 

2 hours ago, steff_92 said:

want to use 2x1TB for DATA and 2x1TB for Parity in case of any one drive failure.

Single parity is all that's required for one drive failure.

Just now, trurl said:

Single parity is all that's required for one drive failure.

You could have lots of data disks, and single parity would still allow you to recover from one drive failure.

3 hours ago, steff_92 said:

For the trim i'm aware, and shutdown the auto schedule triming process.

Unraid will not trim array disks regardless of schedule. Trimming SSDs in the array is simply not allowed.

Thats a new moment that i wasn't aware.

 

If i use 3x1TB for DATA, and just 1x1TB for parity, i'm secured from one frive failure.

 

If any drive of the 3 for DATA dies, the system can recover from the one from parity although those 3x1TB could be full used?

And what if 2 drives are dead, does single parity can help?

 

If i use 2x1TB for DATA, and 2x1TB for parity, i'm secured from two frive failure?

Edited March 23, 20251 yr by steff_92

5 hours ago, steff_92 said:

Thats a new moment that i wasn't aware.

 

If i use 3x1TB for DATA, and just 1x1TB for parity, i'm secured from one frive failure.

 

If any drive of the 3 for DATA dies, the system can recover from the one from parity although those 3x1TB could be full used?

And what if 2 drives are dead, does single parity can help?

 

If i use 2x1TB for DATA, and 2x1TB for parity, i'm secured from two frive failure?

If you have 1 parity drive you can only lose 1 data disk. If you lose 2 data disks and only have a single parity drive, you can’t rebuild either of them and will lose the data that was on those two disks. 
 

if you have 2 party drives you can lose up to 2 data disks and still recover the data.

7 hours ago, steff_92 said:

the system can recover from the one from parity although those 3x1TB could be full used?

Parity is basically the same concept wherever it is used in computers and communications. Parity is just an extra bit that allows a missing bit to be calculated from all the other bits. The parity disk provides the extra bits that allows the missing disk to be calculated from all the other disks.

On 3/22/2025 at 2:13 PM, trurl said:

https://docs.unraid.net/unraid-os/overview/nas/#parity-protected-array

Parity contains none of your data. It doesn't even know anything about files. It is all just parity bits.

 

Parity is not a substitute for backups, whether Unraid or some other parity implementation.

Thanks for helping me, and resolving my missunderstandings.