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Is it possible to remove more then 1 data drive at the same time using the supported procedure?


b0m541

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My array uses 2 parity drives.

I want to use the data drive removal procedure supported by limetech, not the one involving zeroing the drives.

 

Using the following supported procedure (https://wiki.unraid.net/Manual/Storage_Management#Removing_data_disk.28s.29) to remove data drives, is it mandatory to run the procedure for each single data drive to be removed separately, or is it possible to empty several data drives and then remove them all together in one step to only need to rebuild parity once?

 

 

 

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I executed the procedure as described under the link in my previous post.
It went a little bit different as in the description: unraid did not present an option to say "Partity is valid". It just wanted confirmation that I really want to start the array. The array is running now with 2 data drives being unassigned  (and showing up in "Unassigned Devices" (just according to my plan).
However, in "Array Operation" it says "Started, Array unprotected"

In contrast to this it says in the "Main" view: Parity is valid.

 

Reminder: 2 data drives unassigned, and there are 2 parity drives.

 

Observing the Reads and Writes under "Main>Array Devices" it seems like it is doing a parity check or rebuild: it is reading from all drives and writing to the parity drives.

But - nowhere on the UI it is saying that a parity rebuild is running.

 

This behavior is  - at least to me - confusing (mixed signals: Array unprotected vs Parity is valid; not saying that a parity rebuild is in process).


Is it in fact rebuilding the parity now? How can I confirm this?

Or do I need to trigger a parity rebuild? How? (6.9.2)

 

 

Edited by b0m541
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I am not a friend of publicly posting a whole lot of data mostly unrelated to the problem. If you let me know in which files to look, I happily do that on my own. The keyword "parity" does not occur in diagnostics files in "logs".

 

The data transfers were not caused by a parity rebuild, I found a container that continuously write to a drive. After stopping this container there are mostly 0 reads and writes -> not a parity rebuild ongoing.

 

So the question is, why unraid did not ask whether the parity is still valid and why it did not start a parity rebuild.

 

Even more important, how would I trigger a parity rebuild now manually?

 

Edited by b0m541
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As far as I can see I can only start a Read Check, which is peculiar. The Wiki says:

"A Read Check is also the type of check started if you have disabled drives present and the number of disabled drives is larger than the number of parity drives." (https://wiki.unraid.net/Manual/Storage_Management#Read_check)

 

Since I have 2 parity drives and I unassigned 2 drives I should be able to run a parity check or parity rebuild?

This is what my original question was about: May i unassign 2 drives at the same time and then run a parity rebuild once? The answer was positive.

Obviously it does not work like that.

 

 

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Due to lack of options I repeated this procedure: https://wiki.unraid.net/index.php/UnRAID_6_2/Storage_Management#Reset_the_array_configuration

 

This time the result was as described in the Wiki, the content of the parity drives was invalidated and a parity rebuild started when I started the array.

 

I do not understand why that did not happen the first time, but now it works.

 

Edited by b0m541
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Just now, b0m541 said:

Due to lack of options I repeated this procedure: https://wiki.unraid.net/index.php/UnRAID_6_2/Storage_Management#Reset_the_array_configuration

 

This time the result was as described, the content of the parity drives was invalidated and a parity rebuild started when I started the array.

 

I do not understand why that did not happen the first time, but not it works.

 

Perhaps you did not successfully run the New Config step?    If so that would have explained your symptoms.

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19 minutes ago, JorgeB said:

It does, but without the diags can't say what the problem is, you can also post a screenshot of the array devices.

Fair enough, but to be also fair and clear, I also asked how the parity build can be manually triggered.

That question could have been answered without access to the diags. That would have been greatly appreciated.

Just my feedback.

 

 

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On 9/17/2021 at 7:29 PM, JorgeB said:

Not without knowing the array status, that's why wee need the diags, or at least a screenshot of the array devices like mentioned.

 

Something I did not know before asking (which is why I asked) is that the parity will be rebuilt after successfully running "New config". Next time I know it.

 

To be honest I do not see what a look at the diags will change about that: The question was how a parity rebuild can be manually triggered.

And that can be answered with "run new config" no matter what the diags are saying.

 

I perceive a tendency of some people primarily asking for diags, even if the answer to a question does not depend on the data in the diags, and rather not answering a question that could be answered easily and correctly without looking at the diags.

 

People from different places have different notions of privacy, and for some - including me - needing to publicly post diags to get an answer to a question that can be answered without diags feels not right.

 

To me it seems disproportionate, similar as when asking a physician which side effects a certain medication can have and the physician not answering that question before you "please get undressed except for the underpants". Of course the example is exaggerated, but here everything is public and archived for a long time, so that provision of information requires more consideration.

 

Coming back to the concrete case, providing a screenshot is less of a privacy problem and I would have done that, had I not by then found a solution on my own.

 

 

Edited by b0m541
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13 minutes ago, b0m541 said:

asking for diags, even if the answer to a question does not depend on the data in the diags, and rather not answering a question that could be answered easily and correctly without looking at the diags.

 

Users often don't know what they don't know, and there may be things they aren't asking about that would be critical to giving good advice.

 

13 minutes ago, b0m541 said:

Something I did not know before asking (which is why I asked) is that the parity will be rebuilt after successfully running "New config". Next time I know it.

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12 minutes ago, trurl said:

Users often don't know what they don't know, and there may be things they aren't asking about that would be critical to giving good advice.

 

I am sure there are always good intentions behind that, otherwise someone would not take the time to respond.

Assuming that each user knows as few as possible and thus to get as much data as possible is a way to reduce back and forth, I get that.

Just another example: Have you ever called a technical hotline and been treated like you know as few as possible ("have you turned on the device?", "is the power plug in?"). how does that feel? (I am not saying this is what happened here, but it is emphasizing the underlying assumption that someone doesn't know anything about the problem domain)

I guess its impossible to know what someone knows when asking a question, but the person does not know the answer :) and the person may know a shitload more than you assume.

I personally prefer to get targeted questions to provide information on point that is needed. it also ensures that I learn how to solve this problem on my own the next time.

Just my 2 cents.

 

 

 

 

Edited by b0m541
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The issue with assuming the user already knows anything is that many people "know" things that are flat out wrong.

 

Almost every question possible has already been asked on the forum at some time, so when someone asks the same question that has been answered many times in the past, we assume they haven't searched for answers, and just want the best advice to not lose data. That involves getting a sense of the overall health of the machine, something that is easy to see in the diagnostics file, but tough to get good answers from someone unfamiliar with the inner workings of the product.

 

One of the worst offenders is people "KNOWING" that rebuilding an unmountable drive will reconstruct their data and make the drive mountable, even though a disabled drive and unmountable drive are totally different conditions with different solutions. Recovering from a situation like that improperly can put the machine on a razor's edge away from losing data permanently.

 

We would much rather err on the side of collecting too much information and keeping someone from losing data than flippantly handing out only the asked answer and having major data loss. I guess it shouldn't bother me when someone shoots themself in the foot and loses data, but it does bother me, and I do everything I know to help prevent it.

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10 minutes ago, b0m541 said:

Ulitmately it is the user's data, maybe the user should decide :)

 

Or: offer to look the diags that the user puts somewhere by using the URL they provide. There is no technical need to publish the diags publicly basically forever. What about that?

Users can always edit a posting to remove the diagnostics at a later point if they want to (and many that worry about privacy do).   I know I am personally disinclined to follow a link to an external site to look at diagnostics.

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20 minutes ago, b0m541 said:

offer to look the diags that the user puts somewhere by using the URL they provide.

Yeah, No.

I'm not clicking on links to some random filesharing site.

21 minutes ago, b0m541 said:

Ulitmately it is the user's data, maybe the user should decide

They decided to ask for help after exhausting their knowledge on the subject. As unpaid volunteers, all we ask is the user provide a good picture of the situation so we don't have to spend hours going back and forth figuring out what the user does or doesn't know, what steps they already may have tried, etc, etc.

 

We are just a group of users trying to help each other.

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1 hour ago, b0m541 said:

Yes i have. They have a lot of non-anon data, e.g. account names, and any combination of that many tech parameters would identify each system individually. It is a catch 22 if you make full diags your primary data source instead of guiding the user by educated questions.

 

Would you kindly submit a feature request detailing what additional information should be anonymized. That way the developers have a better idea of what's needs to be improved. Guiding developers would be beneficial to everyone.

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