ZFS top-level vdev removal - revisited
I would like to give you some additional information about the top-level device removal.
- Other than stated by me in my last blog entry or the documentation you can't do a top-level vdev removal on a mirror in SRU6 or SRU7 (the ones i have checked). When you want to try this feature, you need to use the first available version of 11.4 at the moment. In that version the command will execute.. Or you use a set of striped disks. So if you see the following, you are doing nothing wrong, it simply currently don't work.
I will keep you notified on this by writing another blog entry about this, as soon as it works correctly.
- There was an ongoing question if the empty virtual vdev, that is created on the remaining disks of the pools, can be removed. If you look at the
Usedcolumn in the output there are always some residual meta data on them, a few kilobytes, so they are not totally empty. However it does no harm to have them in the configuration, they are simply left out of the process of writing as soon as they are created and out of the process of reading as soon they are empty. You have use diagnostic tools as
zdbto see them at all. So the answer to this is "No, you can't"