Error 945 : Database cannot be opened due to inaccessible files or insufficient memory or disk space. See the SQL Server error log for details

This is one of the common issue which I have seen. Today I received a ticker from QA team saying one of the database is not accessible. I checked with the team on what exactly they are doing on the database. I came to know the team was processing the data which increased the many databases sizes which lead to Disk space issue. 

Due to there was no free space on the disk for the database to grow further, one of the database went to shutdown mode. You can check the database status from below query. 

use master
select databaseproperty('DBName', 'isShutdown')

Fix/Solution/WorkAround:

1. Took the database offline and brought back online. Query for the same 

use master
alter database DBName set offline


use master
alter database DBName set online

2.  If possible add more hard drive space either by removing of unnecessary files from hard drive or add new hard drive with larger size.

3.  Check if the database is set to Autogrow on.

4. Check if the account which is trying to access the database has enough permission to perform operation.

5. Make sure that .mdf and .ldf file are not marked as read only on operating system file system level.