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TommyJohn

Proper method to remove drive from Array

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New user here in trial period. So far I'm pretty impressed with Unraid and think I will be moving to the licensed version. After comparing FreeNAS I think Unraid is the more flexible solution for my needs. 

 

I've sucessfully created an array with 4x3tb drives and dual parity. I have a separate SSD intended for VMs but I think I incorrectly added the SSD to the array which would not be the recommended approach? Using the unassigned drives plugin is the better method? I do not use the SSD for cache, this is purely a media server. 

 

So now I need to remove the ssd from the array, but I'm confused as to the best approach. My ssd is not mounted yet so do I have to rebuild the parity since it shouldnt be affected? I looked at the options here and am unsure of the best procedure:

 

https://wiki.unraid.net/Shrink_array

 

The The "Clear Drive Then Remove Drive" Method only seems to be valid if the drive is mounted, which mine is not. 

Any guidance you guys can provide would be helpful. 

Thanks

 

image.thumb.png.6ccc97b61893fbd21324dffd81364d0c.png

 

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I wouldn't bother with "Clear Drive then Remove" method. It isn't going to save any time and can be difficult to get right. Just rebuild parity.

 

Tools - New Config, Retain All. Then unassign disk5, DON'T check parity is valid box, start array to begin rebuild. You can deal with SSD after parity rebuild completes.

 

Some people put SSDs as Unassigned Devices as you are suggesting, but that is usually in addition to a cache disk. If you assign the SSD to cache you can use it however you want and since Unraid will manage it for you it is simpler to do it that way.

 

Cache disk isn't only for caching user shares. Each user share has a setting that controls whether and how it uses cache. You don't have to cache anything and the default for most shares is to not use cache.

 

A few special purpose shares default to "prefer" cache, which is exactly those shares you want to live on SSD anyway, such as dockers.

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thanks trurl! I'll use this method and report back if I have any issues. 

 

Thanks for the tip regarding the cache drive, i thought it was only used was purely for that purpose. 

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Be aware that using a RAID controller for unraid is a bad idea.

Please read this entire thread.

 

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13 hours ago, jonathanm said:

Be aware that using a RAID controller for unraid is a bad idea.

Please read this entire thread.

 

Hi Jonathan, yes I did read about raid controllers prior to ordering my server and from what I understood the issues with certain RAID controllers (not specific to the H700) were not passing along SMART info and not reporting the device size correctly. My controller is currently passing both of those without issue However I did read that if the H700 fails then my only recourse is to get another H700 in its place.  

 

If I were to swap out the H700 for say an H200, would I have to re-format and re-transfer all my data or would the new card handle everything like nothing had changed?

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If I were to swap out the H700 for say an H200, would I have to re-format and re-transfer all my data or would the new card handle everything like nothing had changed?

At the very least would need to do a new config and reassign all disks since each disk identification would change, other than that there could also be some issues with the partitions since some raid controllers write to the mbr.

 

 

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5 minutes ago, TommyJohn said:

If I were to swap out the H700 for say an H200, would I have to re-format and re-transfer all my data or would the new card handle everything like nothing had changed?

Unraid would see that all of your drives were different, and would refuse to start. It uses the serial numbers to keep track of drive assignments, so the ID string that the original H700 assigned would no longer be valid. Same thing would happen if you put in a new H700, all the disk ID's would be different.

 

You should manually keep track of which serial number drive is assigned to which logical slot in the unraid array so you can reconstruct the array if something breaks or changes.

 

As far as re-formatting, that depends on how the H700 passes the drives on to unraid. If the drive content is presented identically, then no change is needed after you tell unraid which drive belongs in which logical slot. If, however, the RAID controller does something cute like truncate all the drives by a small amount to ensure identical sizing or keeps RAID bookkeeping info on the drive, then it's possible they would no longer be recognized as having valid partitions.

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Worst case I have all my data backed on other drives so I can start fresh if necessary, would just like to avoid it. 

 

I'm looking at the H200.. how would it support 12 drives like the H700? It seems to only support 8 drives, so does the SAS expander on the R510 backplane take care of the rest? 

Edited by TommyJohn
updated info

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4 hours ago, TommyJohn said:

It seems to only support 8 drives, so does the SAS expander on the R510 backplane take care of the rest? 

Yes

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