Hit an unusual problem on an Isilon cluster running OneFS 7.2 recently. We were rsyncing in some content from an older system that was attached to a Netapp. The logs of the rsync showed issues trying to sync a number of folders due to the fact it was “a read-only filesystem”.
The only common feature was that within all the affected paths was a subfolder named .snapshot. Not /ifs/.snapshot mind you, this was far down the customers directory structure and the path contained what looked like a valid SyncIQ snapshot path!
After worrying a little that maybe someone had somehow symlinked in some content from a snapshot I realised that it was simply the foldername .snapshot is reserved for, yup you guessed it, snapshot purposes.
Indeed try creating an empty folder and then creating a folder named .snapshot and you’ll find it already exists!