ANd I have no clue what you are talking about as vdevs have no "detaching" button. Disks themselves have a detach button. And if you don't have enough redundancy to support the vdev operating with that disk removed it will return an error that you cannot remove it from the pool.
Not sure what you are talking about, but vdev is not disk unless you are doing single disk vdevs. ANd in that case a detach button will exist but if you try to use it it won't work.
Actually I know this one. It's a command line for >zpool detach, you can do it to a physical drive of a mirror set vdev. It's used to detach half of a mirror, and returning the vdev to a single drive stripe vdev.
http://docs.oracle.com/cd/E19120-01/open.solaris/817-2271/gcfhe/index.html
It's at the bottom of that page.
Though I'm not sure why one would want to return to a single striped drive vdev, unless plans are to end up destroying the zpool to use the disks in a new one.
An example would be expanding your storage incrementally, but you'd want to take it out of production.
Start with a 6 disk Z2
Fill zpool
create 2nd zpool
add 2 disks
attach 2 disk Mirrored,
Fill zpool
add 2 disks
attach 2 disk Mirrored,
Fill zpool
Add 2 disk partitioned to 50%each
loose redundancy during next step (freak out)
detach 1disk first Mirrored
detach 1disk second Mirrored
partition and add 2 disks just removed
create 3rd zpool using 2nd partition of each partitioned drive
backup 2nd zpool to 3rd zpool.
Destroy 2nd zpool
partition and add 2 disk just removed
create 4th zpool Z2 with 1st partiton of 6 drives, or attach as 2nd vdev to 1st zpool
Backup 3rd zpool to 4th zpool.
Destroy 3rd zpool
delete 2nd partition of 6 drives.
expand 1st partition of 6 drives.
expand 4th zpool or expand 2nd vdev of 1st zpool.
I'm still trying to figure out a way to do this without taking the system out of production for the couple of days this is going to take with the large hard drives available these days. I'd also like to figure out a way to do this without losing redundancy, and on the fly in the background. I'd only do this on a home server with very limited user access used to store unimportant data like DVD/Blueray movie backups where I don't mind it being down a couple of days for maintainance.
Actually I'd probably try to plan better and just add the new 6 disk vdev to the 1st zpool once I'd bought all the drives if I could.