mirror镜像盘拆成两个单盘：detach之后再add原来那个pool就行了。
单盘做成镜像：remove之后attach原有的磁盘。
简单讲讲4个命令的用途：
add和remove相对，从pool中添加和移除一个盘（准确的说是分区，下同）。
attach和detach相对，attach，不仅加入了同一个组，还组成镜像了。detach就是从镜像组中抽出了1个盘。
怎么理解？add，简单地物理地放在一起。attach，有接触地在一起，attach之后的两个磁盘。
所以，镜像盘拆成两个单盘的操作就是：detach + add；两个单盘改成镜像盘，就是：remove + attach
root@pve1:~# zpool status
pool: rpool
state: ONLINE
scan: resilvered 1.19G in 00:00:09 with 0 errors on Wed Jun 1 12:38:57 2022
remove: Removal of vdev 2 copied 308K in 0h0m, completed on Wed Jun 1 12:38:24 2022
1.52K memory used for removed device mappings
config:
NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
sda3 ONLINE 0 0 0
sdb3 ONLINE 0 0 0
errors: No known data errors
root@pve1:~# zpool detach rpool sdb3
root@pve1:~# zpool add rpool sdb3
root@pve1:~# zpool status
pool: rpool
state: ONLINE
scan: resilvered 1.19G in 00:00:09 with 0 errors on Wed Jun 1 12:38:57 2022
remove: Removal of vdev 2 copied 308K in 0h0m, completed on Wed Jun 1 12:38:24 2022
1.52K memory used for removed device mappings
config:
NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
sda3 ONLINE 0 0 0
sdb3 ONLINE 0 0 0
errors: No known data errors
此时的磁盘大小，就是sda3和sdb3两个分区加起来的大小了
root@pve1:~# df -h /
Filesystem Size Used Avail Use% Mounted on
rpool/ROOT/pve-1 123G 1.2G 121G 1% /
root@pve1:~# zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
rpool 126G 1.15G 125G - - 0% 0% 1.00x ONLINE -
再组合回去作镜像？
root@pve1:~# zpool remove rpool sdb3
root@pve1:~# zpool attach rpool sda3 sdb3
root@pve1:~# zpool status
pool: rpool
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 Jun 1 13:02:59 2022
1.15G scanned at 294M/s, 621M issued at 155M/s, 1.15G total
635M resilvered, 52.72% done, 00:00:03 to go
remove: Removal of vdev 4 copied 64K in 0h0m, completed on Wed Jun 1 13:02:27 2022
2.37K memory used for removed device mappings
config:
NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
sda3 ONLINE 0 0 0
sdb3 ONLINE 0 0 0 (resilvering)
errors: No known data errors
attach回去的时候要指定attach（镜像）的是哪块盘，我上面的是sda3。
稍稍等待，它自动同步数据，已完成。
root@pve1:~# zpool status
pool: rpool
state: ONLINE
scan: resilvered 1.19G in 00:00:08 with 0 errors on Wed Jun 1 13:03:07 2022
remove: Removal of vdev 4 copied 64K in 0h0m, completed on Wed Jun 1 13:02:27 2022
2.37K memory used for removed device mappings
config:
NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
sda3 ONLINE 0 0 0
sdb3 ONLINE 0 0 0
errors: No known data errors
打完收工。
另外补充一点：
如果你当初安装pve时填写的邮箱是真实的话，mirror数据同步完成之后，你会收到一封已完成的邮件，比如这样的：