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joel80

Tutor

Dec 02, 2015

how to remove a hard disk clean from a raid (RN 314, using SSH)

Hey there,

i would like to remove a specific hard drive from the volume cleanly.

First, is my plan very risky, even possible at all in this way?

Afaik i would first use:

btrfs device delete <device> /data

And then start a rebalancing.

My problem is: which device should i remove? i got the serial and some technical data of the harddrive, i want to remove.

i checked the raid:

root@NAS:/dev# btrfs filesystem show


Label: '7c6e9fa0:root'  uuid: 4e2825bc-f7ec-4c5d-8ffa-9bf9b1f6af0X
        Total devices 1 FS bytes used 294.55MiB
        devid    1 size 4.00GiB used 1.63GiB path /dev/md0

Label: '7c6e9fa0:data'  uuid: 1698d7f7-05b1-47c6-b9ac-47ae7d32af4X
        Total devices 1 FS bytes used 3.29TiB
        devid    1 size 5.44TiB used 3.31TiB path /dev/md127

So, how can i identify the right dev to remove, using the serial of the hard drive?

To remove the hard drive instantly, delete the missing drive and rebuild the raid is very risky i think ;-)

Thank you for any hints.

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StephenB
Guru - Experienced User
Dec 02, 2015
What is the larger goal?

-replace a disk

-create a smaller RAID array

-???
- joel80
  Tutor
  Dec 02, 2015
  I want to find out the cause of my sporadic freezes while accessing smb shares.
  
  It might be a single hard drive, which i installed some months ago - i suppose the freezes occures after installing this drive.
  
  So i want to remove this drive, to see if its working fine then.
  - StephenB
    Guru - Experienced User
    Dec 02, 2015
    
    Have you checked the SMART stats? Normally you'd power down the NAS and test that particular drive with the vendor diags.
    
    You could potentially remove it (with the NAS running) and you'd still have all your data - but no RAID redundancy. Then hot-insert the drive after the balance test - which would rebuild the array. No need for SSH.
    
    Another option is just buy a replacement disk, and replace the one you don't trust.
    
    Do you have backups of the data? There's always some risk when you fiddle with the disks.