When I attempt to turn off scheduled snapshots on some volumes, I get this error message: "volume is in use by other operations (Error: 13158)". The schedule does appear to get turned off, but I believe it remains enabled or somehow gets enabled again. I turned off all the snapshot schedules for some volumes used as VM datastores. Over the weekend, a VM admin did some storage vMotion to change the NFS gateway setting and update ESX and stuff. Well, one datastore filled up because snapshots were enabled on it and they had grown due to the changes he made. This ended up taking down a domain controller and a sql server. We have redundant DC & sql, but some systems are dumb and don't fail-over to other sql & DC's very well, so Citrix was all screwed up, Groupwise was partially broken, and some other vital systems were acting up.
My theory is that I turned off snapshot schedules on all the datastore volumes (which I specifically remember doing - annoyed that it's enabled by default), got the error message, saw that the schedules show as disabled, then went on my merry way. In reality, the schedule was still enabled but wouldn't reflect that until I logged out of that tab in System Manager and logged back in.
Anyone else seeing this or similar issues with snapshot schedules? I am using v2.0.1 so I am going to go update to v2.0.2.
I ignored the issue after growing the volume capacity a bit. A couple weeks later, it let me change the schedule I think. I might have done a fail-over reboot around that time as well. Sorry I don't have a definitive solution for you.