====== ZFS - Replace a Disk ======

  * Offline the disk, if necessary, with the zpool offline command.
  * Remove the disk to be replaced.
  * Insert the replacement disk.
  * Run the zpool replace command. 
  * Bring the disk online with the zpool online command.

----

===== Check the Pool Status =====

<code bash>
zpool status Pool1
</code>

returns:

<code bash>
  pool: Pool1
 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://illumos.org/msg/ZFS-8000-9P
  scan: scrub repaired 0B in 21:37:28 with 0 errors on Sun Nov 15 21:37:28 2020
config:

	NAME                                            STATE     READ WRITE CKSUM
	Pool1                                           ONLINE       0     0     0
	  raidz1-0                                      ONLINE       0     0     0
	    gptid/2d35e96c-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0
	    gptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8  DEGRADED     0     0    40  too many errors
	    gptid/2ddb5cb2-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0

errors: No known data errors
</code>

<WRAP info>
**NOTE:**  This shows that Pool1 is in a **degraded** state. 

It tells me that the device gptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8 is the culprit.

</WRAP>

----

===== Determine Drive Identifier =====

<code bash>
glabel status | grep 2d41
</code>

returns:

<code bash>
ptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8     N/A  ada3p2
</code>

<WRAP info>
**NOTE:**  This shows the device that is degraded and has too many errors is /dev/ada3.
</WRAP>

----

===== Determine current Disks =====

<code bash>
ls -1 /dev/gptid/
</code>

returns:

<code bash>
2d35e96c-b611-11ea-be33-00d861fcb7d8
2d41dcbd-b611-11ea-be33-00d861fcb7d8
2dcf9d03-b611-11ea-be33-00d861fcb7d8
2ddb5cb2-b611-11ea-be33-00d861fcb7d8
b649914a-acc6-11ea-8ed5-00d861fcb7d8
b64bffb3-acc6-11ea-8ed5-00d861fcb7d8
</code>

----

===== Offline the Disk =====

Take the Broken Disk offline:

<code bash>
zpool offline Pool1 /dev/gptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8
</code>

----

===== Replace the Physical Disk =====

Replace the physical disk, and check the status again, it should show the disk as offline now.

<code bash>
zpool status Pool1
</code>

returns:

<code bash>
  pool: Pool1
 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://illumos.org/msg/ZFS-8000-9P
  scan: scrub repaired 0B in 21:37:28 with 0 errors on Sun Nov 15 21:37:28 2020
config:

	NAME                                            STATE     READ WRITE CKSUM
	Pool1                                           ONLINE       0     0     0
	  raidz1-0                                      ONLINE       0     0     0
	    gptid/2d35e96c-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0
	    gptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8  OFFLINE      0     0    40  too many errors
 	    gptid/2ddb5cb2-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0

errors: No known data errors
</code>


----


===== Determine current Disks Again =====

This should not contain details of the newly installed disk.

<code bash>
ls -1 /dev/gptid/
</code>

returns:

<code bash>
1d41dcbd-b611-11ea-be33-00d861fcb7d8
2d35e96c-b611-11ea-be33-00d861fcb7d8
2dcf9d03-b611-11ea-be33-00d861fcb7d8
2ddb5cb2-b611-11ea-be33-00d861fcb7d8
b649914a-acc6-11ea-8ed5-00d861fcb7d8
b64bffb3-acc6-11ea-8ed5-00d861fcb7d8
</code>

<WRAP info>
**NOTE:**  Notice that **1d41dcbd-b611-11ea-be33-00d861fcb7d8** is newly there compared to when this was originally checked earlier.

Also, the old disk **2d41dcbd-b611-11ea-be33-00d861fcb7d8** is probably gone too.

</WRAP>

----


===== Do the Replacement =====


<code bash>
zpool replace POOLNAME OLDDRIVE NEWDRIVE

zpool replace Pool1 /dev/gptid/2d41dcbd-b611-11ea-be33-00d861fcb7d8 /dev/gptid/1d41dcbd-b611-11ea-be33-00d861fcb7d8
</code>

----

===== Check the Status =====

It should now be rebuilding / resilvering.

<code bash>
zpool status Pool1
</code>

returns:

<code bash>
  pool: Pool1
 state: ONLINE
status: One or more devices is currently being resilvered.  The pool will
    continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
  scan: resilver in progress since Wed Aug 10 12:12:12 2016
        241.4G scanned out of 8.55T at 432M/s, 6h12m to go
        85.21G resilvered, 10.69% done
config:

	NAME                                            STATE     READ WRITE CKSUM
	Pool1                                           ONLINE       0     0     0
	  raidz1-0                                      ONLINE       0     0     0
	    gptid/2d35e96c-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0
            gptid/1d41dcbd-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0  (resilvering)
  	    gptid/2ddb5cb2-b611-11ea-be33-00d861fcb7d8  ONLINE       0     0     0

errors: No known data errors
</code>

<WRAP info>
**NOTE:**  Once the resilver is complete the status should be back to normal.

</WRAP>