A bit of advice concerning parity disk please


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My setup:

1 parity disk

3 data disks

All drives is 4TB WD Red drives.

 

I noticed recently both my parity disk and my disk 1 is exactly the same age, more precise soon to turn 3 years old.

And my friend warned me for having it this way since most likely when one of these drive fails, the other drive will fail aswell when I start to replace the drive with a new drive.

So I bought a new drive which is pre-clearing right now. My main thought was to replace the parity disk and instead use the parity disk as a data disk. But now when I'm thinking about it, is it better to just add another parity disk instead maybe?

 

Edited by truetype
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1 hour ago, truetype said:

My setup:

1 parity disk

3 data disks

All drives is 4TB WD Red drives.

 

I noticed I recently both my parity disk and my disk 1 is exactly the same age, more precise soon to turn 3 years old.

And my friend warned me for having it this way since most likely when one of these drive fails, the other drive will fail aswell when I start to replace the drive with a new drive.

So I bought a new drive which is pre-clearing right now. My main thought was to replace the parity disk and instead use the parity disk as a data disk. But now when I'm thinking about it, is it better to just add another parity disk instead maybe?

 

Your friend seems to have some superstitions. If you don't have any warnings on the Dashboard everything is likely OK. And you don't really have enough data disks to justify dual parity in my opinion.

 

There are many more important things to worry about. Do you have Notifications setup to alert you by email or other agent immediately when Unraid detects a problem? People who actually do get multiple disk problems are usually those who ignored their single disk problem until they got another one.

 

Most of the time when someone has a problem after replacing a disk, it is due to disturbing connections on other disks. Double check all connections any time you open the case.

 

And if you do want us to take a look at the health of your disks, go to Tools - Diagnostics and attach the complete diagnostics zip to your next post.

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30 minutes ago, John_M said:

Why don't you post your diagnostics and get an opinion based on the SMART reports of your disks instead of FUD from your friend?

 

3 minutes ago, trurl said:

Your friend seems to have some superstitions. If you don't have any warnings on the Dashboard everything is likely OK. And you don't really have enough data disks to justify dual parity in my opinion.

 

There are many more important things to worry about. Do you have Notifications setup to alert you by email or other agent immediately when Unraid detects a problem? People who actually do get multiple disk problems are usually those who ignored their single disk problem until they got another one.

 

Most of the time when someone has a problem after replacing a disk, it is due to disturbing connections on other disks. Double check all connections any time you open the case.

 

And if you do want us to take a look at the health of your disks, go to Tools - Diagnostics and attach the complete diagnostics zip to your next post.

 

Thank you for your replies guys, you are right it's definately you I listen to in the end you get the final words, and that's why I created this topic. :)

Okey, please have a look at the attached diagnostics and make my life easier for me.

 

untrue-diagnostics-20181204-1957.zip

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55 minutes ago, John_M said:

Your disks are fine. Stop worrying about them. Just follow trurl's advice and act on any warnings you receive.

Alright, thanks for your look. But I wonder, theoretically, if one of those disks start to get a warning the other disk should not be far away from a warning too? Since they are the same age?

As an answer to trurl I have setup agents to notify me when I get warnings, but is it really that safe? In my experience it can go very fast when a disk starts to malfunction to die completely. Isn't it better to be more pro-active then and I replace on of the drives now?

Edited by truetype
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5 minutes ago, truetype said:

Since they are the same age?

How do you know? No two of them have remotely similar serial numbers. You might have bought them at the same time but they could well be from different batches and even ones from the same batch won't behave identically. Most hard disks fail either very early in their lives or at a ripe old age. In fact, a lot of Unraid disks get replaced before they fail because their capacity is no longer considered adequate. Yours are neither young nor old - they're somewhere in the middle and they're fine.

 

I notice you said

4 hours ago, truetype said:

My main thought was to replace the parity disk and instead use the parity disk as a data disk.

which is completely the wrong approach. If you don't have confidence in your parity disk you really don't want to re-purpose it as a data disk. Remember that to rebuild a failed disk you need all the remaining ones to be perfectly readable. In fact, of all the disks in your array, the parity disk is the most expendable because on its own it holds no useful data, whereas any one of your data disks holds a complete file system.

 

4 hours ago, truetype said:

is it better to just add another parity disk instead maybe?

I feel happier with dual parity. I think it's more important, not just on larger arrays, but when larger disks are used because then rebuild times become quite long. Only you can decide whether its a justifiable expense in your case.

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2 hours ago, truetype said:

As an answer to trurl I have setup agents to notify me when I get warnings, but is it really that safe? In my experience it can go very fast when a disk starts to malfunction to die completely. Isn't it better to be more pro-active then and I replace on of the drives now?

Since you are using WD disks one thing you can do to increase the chances of early problem detection is to start monitoring SMART attribute 1, Raw read error rate, if this starts to increase it's a bad sign, though a few errors can be OK.

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18 hours ago, John_M said:

How do you know? No two of them have remotely similar serial numbers. You might have bought them at the same time but they could well be from different batches and even ones from the same batch won't behave identically. Most hard disks fail either very early in their lives or at a ripe old age. In fact, a lot of Unraid disks get replaced before they fail because their capacity is no longer considered adequate. Yours are neither young nor old - they're somewhere in the middle and they're fine.

 

I notice you said

which is completely the wrong approach. If you don't have confidence in your parity disk you really don't want to re-purpose it as a data disk. Remember that to rebuild a failed disk you need all the remaining ones to be perfectly readable. In fact, of all the disks in your array, the parity disk is the most expendable because on its own it holds no useful data, whereas any one of your data disks holds a complete file system.

 

I feel happier with dual parity. I think it's more important, not just on larger arrays, but when larger disks are used because then rebuild times become quite long. Only you can decide whether its a justifiable expense in your case.

Alright thank you very much.

Well since I already have the disk now I think I will use it as a 2nd parity disk anyway. :P

 

17 hours ago, johnnie.black said:

Since you are using WD disks one thing you can do to increase the chances of early problem detection is to start monitoring SMART attribute 1, Raw read error rate, if this starts to increase it's a bad sign, though a few errors can be OK.

Thanks for your input. Ok, great, do you know how I can set unraid to start looking for changes in the SMART attribute 1 and warn me by agent?

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