cannot destroy '<dataset name>': dataset is busy vs iSCSI

[Edward Tomasz Napierała]

On 0818T1958, Eugene M. Zheganin wrote:
> Hi.
> 
> I'm using zvol clones with iSCSI. Perdiodically I renew them and destroy
> the old ones, but sometimes the clone gets stuck and refuses to be
> destroyed:
> 
> (I'm showing the full sequence so it's self explanatory who is who's parent)
> 
> [root at san2:/etc]# zfs destroy esx/games-reference1 at ver5_6       
> cannot destroy 'esx/games-reference1 at ver5_6': snapshot has dependent clones
> use '-R' to destroy the following datasets:
> esx/games-reference1-ver5_6-worker111
> [root at san2:/etc]# zfs destroy esx/games-reference1-ver5_6-worker111
> cannot destroy 'esx/games-reference1-ver5_6-worker111': dataset is busy
> 
> The only entity that can hold the dataset open is ctld, so:
> 
> [root at san2:/etc]# service ctld reload                                    
> [root at san2:/etc]# grep esx/games-reference1-ver5_6-worker111 /etc/ctl.conf
> [root at san2:/etc]# zfs destroy esx/games-reference1-ver5_6-worker111      
> cannot destroy 'esx/games-reference1-ver5_6-worker111': dataset is busy
> 
> As you can see, the clone isn't mentioned in ctl.conf, but still refuses
> to be destroyed.
> Is there any way to destroy it without restarting ctld or rebooting the
> server ? iSCSI is vital for production, but clones sometimes holds lot
> of space.

Could you do "ctladm devlist -v" and see if the LUN for this file somehow
didn't get removed?