I checked our lab cases for this, and found a couple of things that may be helpful.
One suggestion is that the Store was not shut down properly, and will probably take a long time to start. Since the store (in this lab case) has more than 10 TB of data of deduped data, this isn't surprising. Therefore, as a first step, we need to let the store startup run for as long as it needs. We can keep monitoring the Windows Application event log to check if the startup process completed or not. Also, we can try starting the StoreOnce service with logging enabled, so that we can track any other errors that might crop up.
Another suggestion was to see if you are getting any warnings about Low Memory availability, written into the Application or System Event log on the StoreOnce server
If so, there is a Microsoft article about Memory utilization
the Microsoft Dynamic Cache Service as already recommended.
Also, it is suggested that you set two environment variables on the StoreOnce server by editing the file
ProgramData -> Omniback -> omnirc
On the StoreOnce server, stop the Data Protector INET service.
This file does not exist by default. If you don't have it, it can be created using Notepad.
Make sure that the filename has no extension, like ‘txt’ or ‘tmpl’
Restart the Data Protector INET service.
OB2_STOREONCESOFTWARE_MEMORY_METRICS_WARNING_AT=n Default: 25 This variable defines when the low free memory warning is going to be written into event/system log. The unit can be either % or Megabytes based on OB2_STOREONCESOFTWARE_MEMORY_METRICS_UNIT variable.
OB2_STOREONCESOFTWARE_MEMORY_METRICS_ERROR_AT=n Default: 10 This variable defines when the low free memory error is going to be written into event/system log and all transactions to the store are going to be rejected. The unit can be either % or Megabytes based on OB2_STOREONCESOFTWARE_MEMORY_METRICS_UNIT variable.
Also, please be sure that you have the latest StoreOnce patch installed DPWIN_00630 by running the command from the MS-DOS prompt on the cell manager
omnicheck -patches -host [StoreOnce Media Agent hostname] Don't include the [ ] marks
If none of this helps, you will probably need to open a case with the response center, and have StoreOnce debugging enabled and also send the Application and System Event logs from the StoreOnce server