Upgrade my parity drive disk

[[email protected]]

Hello,

 

I have read the instructions of the afformentioned video and I have some questions arround the fact of adding/ replacing a parity drive in the array.

 

Well my array consists of 3 3TB (NAS) hard drives. The description of video is similar to mine with the exception of 1 TB drive data.

First of all I would like to ask if the aformentioned video corresponds to a 0% data loss scenario. What I am asking is: Am I sure that, after applying the instructions of the afformentioned video, Iam not going to lose any data? Please explain it to me with every material you have. I am going sometime in the future to do the following:

 

1) Remove deliberately one data disk from array (preferably the 96% full of capacity) and start the array without him.

2) Stop the array and shutdown pc

3) Replace the 3TB parity drive with a 10TB parity drive (both NAS)

4) Plug to new sata port the new (future) parity drive

5) Start up pc

6) In the array details and before starting the array replace old parity with the new one and in the empty slot where I had the old data drive, I place the old parity drive (both should be blue icons after this)

7) Then I check the checkbox to copy, right besides the start array button and start it.

 

So after finishing these steps, am I going to be sure that nothing is lost, as far as data is concerned?

 

A second option, but also a question is, to add another parity drive of 10TB(NAS), as a second parity drive, since I already have the choice to add a second parity drive and perform the above procedure some other time in the future, with the smallest parity drive of 3TB.

 

Another question is more like an assumption. Are we sure that 0% data loss is ensured by the fact that there is 1 parity of 3TB versus 2 data disks of 6TB in total? Shouldn't I have another parity of 3TB to be sure that I do not lose data? Had I 2 parity disks (3TB each), it conpensates the fact that I am not going to lose data since I have 2 data disks (3TB each). 2 x 3 TB of parity = 2 x 3TB of data = 6TB.

 

This is very important!

 

Please correct me to any of the aformentioned steps and inform me about the correctness of both options.

Edited September 29, 2021 by [email protected]

[Frank1940]

There is not way that you can ever be guaranteed a 0% chance of not having any data loss.  With only a single point of storage, there are many 'nature' events that can cause the loss of your server.  That does even consider the possibility of theft or malicious damage to your server-- either software or physical.

 

For a rough idea of the probability of data loss through disk failures in your Unraid server, you can look at this thread:

 

    https://forums.unraid.net/topic/50504-dual-or-single-parity-its-your-choice/

 

IF you data is truly that valuable, you should be looking at redundant copies of your data offsite in a secure location.  You can google    3-2-1 backup   for more insight. 

[JonathanM]

Are all your current array drives healthy?

 

List your current drives, and then list your desired final configuration.

 

I suspect you are overly complicating things.

 

4 hours ago, [email protected] said:

. Are we sure that 0% data loss is ensured by the fact that there is 1 parity of 3TB versus 2 data disks of 6TB in total? Shouldn't I have another parity of 3TB to be sure that I do not lose data? Had I 2 parity disks (3TB each), it conpensates the fact that I am not going to lose data since I have 2 data disks (3TB each). 2 x 3 TB of parity = 2 x 3TB of data = 6TB.

Parity IS NOT A BACKUP. The parity disks do not contain copies of your data.

https://wiki.unraid.net/Parity

[[email protected]]

Ok let me put my questions in a different manner. I just deliberately remove a 95% capacity data drive, full of real important data from my array. In other words I apply the steps from 1-7 as I told in my first post. Would I result with a 3TB cloned data disk drive with exactly the same data (95% capacity) as the one I extracted and I am keeping it in my hands as an intact disk? Or the new data disk is empty and there is no backup at all?

Edited September 29, 2021 by [email protected]

[JonathanM]

7 minutes ago, [email protected] said:

Ok let me put my questions in a different manner. I just deliberately remove a 95% capacity data drive, full of real important data from my array. In other words I apply the steps from 1-7 as I told in my first post. Would I result with a 3T cloned disk drive with exactly the same data (95% capacity) as the one I extracted in my hands and is completely intact? Or the new data disk is empty and there is no backup at all?

The answer depends on the condition of your array drives.

 

Are all of the remaining drives perfectly healthy?

 

When was the last time you completed a parity check with zero errors?

[[email protected]]

The disks are completely healthy and I performed a parity disk check with 0 errors in the date mentioned in the images below:

 

 

 

Edited September 29, 2021 by [email protected]

[[email protected]]

Hello,

 

currrently I have 1 parity disk of 3TB and 2 data drive disks of 3TB each. Iam thinking of replacing the old parity disk with the new one without following any swap procedure (by doing it immediately and rebuilding array). Do I lose data in this way? Last time I performed a parity check, it was with 0 errors and the health of the current disks is fine

Edited September 29, 2021 by [email protected]

[JonathanM]

19 minutes ago, [email protected] said:

The disks are completely healthy

How are you determining that? SMART tests are a fairly good indicator, but you haven't posted diagnostics from your server so I have no way of verifying what you are saying.

 

If parity is in sync, and all remaining drives are healthy, Unraid will emulate the missing disk exactly as it was at the point it was disabled, and all further operations to that slot will be done by updating the parity disk exactly as it would have been had the drive not been disabled.

 

6 hours ago, [email protected] said:

I have some questions arround the fact of adding/ replacing a parity drive in the array.

 

Normally to upgrade parity you would simply remove the old parity drive and replace it with a new one, or simply assign a new drive to the second parity slot if you wanted dual parity. No need to complicate things by going through a procedure meant for using the current parity disk to replace one of the data drives.

 

1 hour ago, [email protected] said:

I just deliberately remove a 95% capacity data drive, full of real important data from my array.

Why would you do that? It's not necessary if what you want to accomplish is a parity upgrade.

[[email protected]]

Thank you so much for your replies.

 

Attached you are going to find my tower diagnostics. Three other questions I need to ask are:

 

1) With this configuration (2 parity disks 3TB and 10TB, 2 data disks 3TB each), is dual parity going to work as expected?

2) With this configuration (2 parity disks 3TB and 10TB, 2 data disks 3TB each), supposed that I need to also upgrade the second parity in the future with another 10TB parity is it going to enhance something as far as data safety or the capacity of each data disk? For instance if 2 disks fail, is the replacement of 2 new disks going to solve my problems without any loss of data?

 

3) With this configuration (2 parity disks 3TB and 10TB, 2 data disks 3TB each), If None of the disks fail, would I be able to easily replace the 3TB parity disk with a new 10TB without any loss of data?

tower-diagnostics-20210930-0004.zip

 

P.S. You are also going to find attached some smart tests of the disks

tower-smart-20210930-0044.zip tower-smart-20210930-0044 (1).zip tower-smart-20210930-0044 (2).zip

Edited September 29, 2021 by [email protected]

[JonathanM]

Each parity disk must be the same size OR LARGER than any data disk.

Each parity disk operates independently.

Each parity disk combined with all the remaining data disks can rebuild one failed disk.

Parity disks are replaceable at any time, and can be replaced with a disk the same size as the largest data disk or larger.