Is there a way to remove a mistake device

[bitraft]

I try add cache into pool, but run the wrong command:
I run "zpool add rpool /dev/sda4 -f", but I should run "zpool add rpool cache /dev/sda4 -f"

Then I try zpool offline -f rpool sda4 to offline it.

What should I do next, is the pool safe to reboot ?

zpool status
  pool: rpool
 state: DEGRADED
status: One or more devices has experienced an unrecoverable error.  An
	attempt was made to correct the error.  Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
	using 'zpool clear' or replace the device with 'zpool replace'.
   see: http://zfsonlinux.org/msg/ZFS-8000-9P
  scan: scrub repaired 0B in 0 days 01:44:29 with 0 errors on Sun Jan 10 02:08:30 2021
config:

	NAME                                  STATE     READ WRITE CKSUM
	rpool                                 DEGRADED     0     0     0
	  raidz3-0                            ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307JGM1AS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7W9AS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_Z9B4ZRPGS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7XXAS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7Z2AS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7YGAS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7ZBAS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307JGLPAS  ONLINE       0     0     0
	    ata-TOSHIBA_DT01ACA200_307J7X9AS  ONLINE       0     0     0
	  sda4                                DEGRADED     0     0     0  external device fault
errors: No known data errors

[gmelikov]

Unfortunately, zpool remove for vdev doesn't work on pools with raidz vdevs for now. You may convert sda4 to mirror with additional disk via zpool attach, or rebuild pool from scratch.

[bitraft]

After I reboot into the LiveCD, I can not import the Zpool.

zpool import -d /dev/disk/by-id/ -f
   pool: rpool
     id: 16321313318083708896
  state: UNAVAIL
 status: The pool was last accessed by another system.
 action: The pool cannot be imported due to damaged devices or data.
   see: http://zfsonlinux.org/msg/ZFS-8000-EY
 config:

	rpool                                 UNAVAIL  insufficient replicas
	  raidz3-0                            ONLINE
	    ata-TOSHIBA_DT01ACA200_307JGM1AS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7W9AS  ONLINE
	    ata-TOSHIBA_DT01ACA200_Z9B4ZRPGS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7XXAS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7Z2AS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7YGAS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7ZBAS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307JGLPAS  ONLINE
	    ata-TOSHIBA_DT01ACA200_307J7X9AS  ONLINE
	  wwn-0x5002538c40bd67b8-part4        FAULTED  corrupted data

zpool import -o readonly=on -N -R /mnt rpool -f
cannot import 'rpool': one or more devices is currently unavailable
``

How many change the ssd get  corrupted data like this ? I just attach a DISK and try reboot backup then run into this. What should I do next?

[bitraft]

any suggestion?

[bitraft]

After I convert sda4 to mirror, may I remove it from rpool ?

Other question is if sda4 remove from my server, will the OS still boot ?

[gmelikov]

After I convert sda4 to mirror, may I remove it from rpool ?

No

Other question is if sda4 remove from my server, will the OS still boot ?

You can't import this pool without sda4, if your root dir is on this pool, then your OS won't boot.

[bitraft]

Thanks, I guess I need to rebuild it.