This article describes DS-System behavior when it cannot connect to either its database or its online storage. When DS-System service/daemon is running, DS-System must be able to complete its activities with these components in order to function. If the DS-System service/daemon is stopped and any of these components are not available, the DS-System service/daemon will fail to start.
o DS-System connection to its database
o DS-System connection to its online storage
DS-System connection to its database
DS-System must be able to access (query, insert, delete, etc.) its database whenever required.
1.On startup, if DS-System cannot connect to its database:
o it will retry 300 times (in intervals of at least 1 second). If no connection can be established after 300 attempts, DS-System stops and errors will be reported in the Operating System event log.
If DS-System is already running and it fails to connect to its database:
o It will continue retrying the connection until it succeeds. Errors will be reported in the Operating System event log.
o If no connection can be re-established, the DS-System will effectively hang (unless the database responds), requiring a hard stop of the service/daemon. Active transactions may fail, and the effect of such lost transactions cannot be predicted in advance.
o This is the same for Windows and Linux DS-Systems.
DS-System connection to its online storage
If DS-System loses the connection to the online storage, it will switch to a "suspended" state.
If Windows DS-System loses the connection to any of the DS-System storage locations, DS-System will stop any running activities. The service will remain running, but it will switch to a suspended-state, retrying the connection to the DS-System Online Storage every minute until it becomes available again. Windows DS-System can detect in less than five minutes if it loses connection with a storage location, therefore the response time is fast for this situation.
If Linux DS-System loses the connection to any of the DS-System storage locations, DS-System will allow the running activities to continue however the write to storage will stop, since the storage is not available. The DS-Clients will wait for the message queue to be freed before sending more data. Linux DS-System cannot immediately detect if it loses connection with a storage location. Therefore the mount point monitoring function must be used to define the storage locations that the Linux DS-System will monitor (every 5 minutes). This only applies for NFS configurations (i.e. the recommended setup for Linux DS-System). If the Linux DS-System is using a local attached disk or cluster file system, it will not switch to a "suspended" state. In addition to this, even when using NFS, it depends on NFS settings (NFS may be configured with time-outs). This means even if Linux DS-System switches to "suspended" state (on a failed mount-point check), the NFS might hang during the check.