DataCore SANsymphony-V 9.0 PSP4 Update 2 - Update recommended
Yesterday I got an e-mail from DataCore in which Update 2 for DataCore SANsymphony-V PSP4 was announced. DataCore found a critical issue in all releases since SANsymphony-V 9.0 PSP3. According to the releases notes a situation can occur, in which storage space reclamation and migration can happen at the same time. This can lead to a situation in which two storage allocation unit (SAU) can point to the same disk offset. If this happens, the disk pool can be marked offline.
From my point of view only those customers are directly affected that use DataCore Auto-Tiering. Nevertheless I recommend to all DataCore customers to update to the latest SANsymphony-V release. You can download the latest release from the DataCore Support Portal. The update can be done online if you have a mirrored DataCore enviroment.
Update
Patrick mentioned in his blog, that SAU migration can also occur in other situations, e.g. adding or removing disks to or from a disk pool. The space reclamation starts as soon as a virtual disk is deleted or SSV detects a all zeroed virtual disks. So deleting a virtual and adding a physical disk to a pool can also lead to a offline disk pool. Thanks to Patrick for clarification.