[SOLVED] Cleared Flag on Previously Deployed Parity Drive Now Data Drive

Hi All,

If you can't gleam it from the subject I had a WD 3TB Red drive I had previously in service as my Parity Drive on my Main Server. Having safely replaced it with a Seagate 8TB drive I went to deploy it into the main array. Given that it was a previously cleared and deployed drive in Unraid I had expected to just have to format it and add it to the array.

Unfortunately Unraid did not recognise that it had previously been cleared and wanted to do it again. I was "almost" certain that previously deployed drives did not have to be cleared again but then again I couldn't remember if this was just for past deployed data drives and did not extend to parity drives.

As I didn't want my Unraid Server to be unresponsive while the drive was cleared I did not start the process and put it through a pre_clear instead. Which it is happily doing now. However I thought I would post this observation on the off chance it is a bug with Unraid recognising the clear flag on the drive or something else.

I was toying with which forum to put this in and figured v6 General Support was better than Hard Drives and I am not sure it is a bug as I can't find any references to whether this is expected behaviour or not.

Thoughts?

Daniel

A cleared drive is full of binary zeroes. When you put a cleared drive into service it is not cleared any more.

Now preclearing a drive does give it a good workout and once done that workout may no longer be required, but it you want it cleared you would have to clear it again if it had been in service as a parity drive.

When upsizing parity, though, there is no need to clear the old parity disk if you do things properly. If you look in my sig you will find a link to a post about upsizing parity and reusing the old parity as a data disk that is very efficient and does not require preclearing the old parity.

A cleared drive is full of binary zeroes. When you put a cleared drive into service it is not cleared any more.

 

Now preclearing a drive does give it a good workout and once done that workout may no longer be required, but it you want it cleared you would have to clear it again if it had been in service as a parity drive.

 

When upsizing parity, though, there is no need to clear the old parity disk if you do things properly. If you look in my sig you will find a link to a post about upsizing parity and reusing the old parity as a data disk that is very efficient and does not require preclearing the old parity.

I followed your instructions (Your post is in my best practices folder) actually which is why I am posting. Once I had replaced the parity drive and all was built and checked I added the previous parity drive to the array BUT it did not give me an option to format it. All I got was a prompt to clear it.

A cleared drive is full of binary zeroes. When you put a cleared drive into service it is not cleared any more.

 

Now preclearing a drive does give it a good workout and once done that workout may no longer be required, but it you want it cleared you would have to clear it again if it had been in service as a parity drive.

 

When upsizing parity, though, there is no need to clear the old parity disk if you do things properly. If you look in my sig you will find a link to a post about upsizing parity and reusing the old parity as a data disk that is very efficient and does not require preclearing the old parity.

 

I followed your instructions (Your post is in my best practices folder) actually which is why I am posting. Once I had replaced the parity drive and all was built and checked I added the previous parity drive to the array BUT it did not give me an option to format it. All I got was a prompt to clear it.

did you use the latest version of the preclear script ?

did you use the latest version of the preclear script ?

The older parity drive was pre_cleared in February 2013 and has been in service ever since. I cannot remember what pre_clear script version we were on back then but I know we were on v5 Beta or RC at the time. I will have used the pre_clear script latest at the time.

Maybe thats it - given I have upgraded to v6 with drives previously deployed in v5 (and there have been newer pre_clear scripts developed since that disk was deployed) the old parity drive which was deployed in v5 and has been in service from then through v6 upgrade was not flagging as previously cleared and or not able to be added to the array without having to be cleared again when I wanted to add it to the array as a data drive!?? Makes sense I guess.

I followed your instructions (Your post is in my best practices folder) actually which is why I am posting. Once I had replaced the parity drive and all was built and checked I added the previous parity drive to the array BUT it did not give me an option to format it. All I got was a prompt to clear it.

Refer to the bolded sections below. I think you may have missed these steps if you are attempting to add the old parity drive to the array after the new parity was built.

6. Do a new configuration, and assign the new parity, all data disks to their respective slots. And assign the current parity to the next data slot (if you intend to use it as a data drive).

7. Start the array. Let parity build. Do not format the unformatted old parity disk. Do not write to the array.

8. Should something go wrong like a red ball, save the syslog, stop the array, shutdown the server, fix loose connection (often the cause of the red ball), restore the USB (config directory) backup, and reboot. The old parity will be back in its prior place and the red ball will likely be gone. Run a parity check. You may get a few sync errors early. It's ok. Go back to step 3. Or ask for advice on the forum if drive red balls again.

9. If all goes well with the build do a parity check.

10. If the parity check goes well, then format the old parity, delete the USB (config directory) backup (it is dangerous now and you never want to use it again), and write to the array all you want!

The version of the preclear script is probably not germain.

I followed your instructions (Your post is in my best practices folder) actually which is why I am posting. Once I had replaced the parity drive and all was built and checked I added the previous parity drive to the array BUT it did not give me an option to format it. All I got was a prompt to clear it.

 

Refer to the bolded sections below. I think you may have missed these steps if you are attempting to add the old parity drive to the array after the new parity was built.

 

6. Do a new configuration, and assign the new parity, all data disks to their respective slots. And assign the current parity to the next data slot (if you intend to use it as a data drive).

 

7. Start the array. Let parity build. Do not format the unformatted old parity disk. Do not write to the array.

 

8. Should something go wrong like a red ball, save the syslog, stop the array, shutdown the server, fix loose connection (often the cause of the red ball), restore the USB (config directory) backup, and reboot. The old parity will be back in its prior place and the red ball will likely be gone. Run a parity check. You may get a few sync errors early. It's ok. Go back to step 3. Or ask for advice on the forum if drive red balls again.

 

9. If all goes well with the build do a parity check.

 

10. If the parity check goes well, then format the old parity, delete the USB (config directory) backup (it is dangerous now and you never want to use it again), and write to the array all you want!

 

The version of the preclear script is probably not germain.

Oh #$@&%*! #$@&%*! #$@&%*!!!!!!! I didn't do the new config. Sigh. RTFM Daniel for God's sake!

Thank you for the reply Brian. Sorry to have wasted your time.

Once you have built parity, any drive added to a new slot must be clear; i.e., all zeros, or it would invalidate parity. Brian's method effectively adds the drive without parity and then builds parity against the bits already on the drive.

Once you have built parity, any drive added to a new slot must be clear; i.e., all zeros, or it would invalidate parity. Brian's method effectively adds the drive without parity and then builds parity against the bits already on the drive.

Of course that makes sense now. I annoy myself (as well as others I am sure) sometimes.

The drive gets another work out, I guess it's not the end of the world.

Thank you.

Oh #$@&%*! #$@&%*! #$@&%*!!!!!!! I didn't do the new config. Sigh. RTFM Daniel for God's sake!

 

Thank you for the reply Brian. Sorry to have wasted your time.

If you are upsize or replace a red-balled data disk, you can only rebuild that one disk.

But upsizing/replacing parity is a special case. Functionally there is absolutely nothing different about rebuilding parity and doing a new config with a new parity disk. With the new config you just have to be careful to redefine the array properly (old versions of unRaid allowed equivalent of new config without losing disk assignments - which I liked better).

Look at the bright side - your small faux pas may have helped a lot of other users learn a useful tweak!

Cheers!