Database cannot be opened due to inaccessible files or insufficient memory or disk space

Database cannot be opened due to inaccessible files or insufficient memory or disk space

Msg 945, Level 14, State 2, Line 1

Database 'db' cannot be opened due to inaccessible files or insufficient memory or disk space. See the SQL Server errorlog for details.

Solution:

Check Microsoft SQL Server error log and determine reason for the cause.

If it is because of a persistent I/O error related to Application Programming Interface, a torn page, or other hardware issues, resolved it and restore it with help of backup. But if there is no availability of backups then try DBCC CHECKDB repair option.

 If possible add some disk space to files drive or cleanup some disk space.

Verify the permissions of user account.

Verify if the database is property is set to AutoGrow On.

.mdf and .ldf files should not be marked as Read Only on windows level.

If none of the above solved Issue: Try this

1. Change the database to offline to clear the db status

use master

alter database dbname set offline

2. Now change the database to online, at this step log file and data files will be verified by sql server

use master

alter database dbname set online

DBCC CHECKDB :A database snapshot cannot be created because it failed to start.

Disk space issues during DBCC CHECKDB

Sometimes an issue arises when the hidden database snapshot runs out of space. Because it’s implemented using alternate streams of the existing data files, the database snapshot consumes space from the same location as the existing data files. If the database being checked has a heavy update workload, more and more pages are pushed into the database snapshot, causing it to grow. In a situation where the volumes hosting the database don’t have much space, this can mean the hidden database snapshot runs out of space and DBCC CHECKDB stops with an error. An example of this is shown here (the errors can vary depending on the exact point at which the database snapshot runs out of space):

DBCC CHECKDB ('SalesDB2') WITH NO_INFOMSGS, ALL_ERRORMSGS;
GO
Msg 1823, Level 16, State 1, Line 5
A database snapshot cannot be created because it failed to start.
Msg 1823, Level 16, State 2, Line 1
A database snapshot cannot be created because it failed to start.
Msg 7928, Level 16, State 1, Line 1
The database snapshot for online checks could not be created. Either the reason is given in a previous error or one of the underlying volumes does not support sparse files or alternate streams. Attempting to get exclusive access to run checks offline.
Msg 5128, Level 17, State 2, Line 1
Write to sparse file 'C:\SQLskills\SalesDBData.mdf:MSSQL_DBCC20' failed due to lack of disk space.
Msg 3313, Level 21, State 2, Line 1
During redoing of a logged operation in database 'SalesDB2', an error occurred at log record ID (1628:252:1). Typically, the specific failure is previously logged as an error in the Windows Event Log service. Restore the database from a full backup, or repair the database.
Msg 0, Level 20, State 0, Line 0
A severe error occurred on the current command. The results, if any, should be discarded.

In this case, the solution is to create your own database snapshot, placing the snapshot files on a volume with more disk space, and then to run DBCC CHECKDB on that. DBCC CHECKDB recognizes that it’s already running on a database snapshot and doesn’t attempt to create another one. If a database snapshot was created by DBCC CHECKDB, it’s discarded automatically after the consistency-checking algorithms are complete.
While it runs, DBCC CHECKDB creates a database snapshot (if needed) and suspends the FILESTREAM garbage collection process. You might notice garbage collection run at the start of the consistency checking process; the creation of the hidden database snapshot starts with a checkpoint, which is what triggers FILESTREAM garbage collection. The suspension of garbage collection activity allows the consistency-checking algorithms to see a transactionally consistent view of the FILESTREAM data on any FILESTREAM data containers

Alternatives to using a database snapshot

A database snapshot isn’t required under the following conditions.

• The specified database is a database snapshot itself.
• The specified database is read-only, in single-user mode, or in emergency mode.
• The server was started in single-user mode with the –m command-line option.

In these cases, the database is already essentially consistent because no other active connections can be making changes that would break the consistency checks.
A database snapshot can’t be created under the following conditions.

• The specified database is stored on a non–NTFS file system, in which case a database snapshot can’t be created because it relies on NTFS sparse-file technology.
• The specified database is tempdb, because a database snapshot can’t be created on tempdb.
• The TABLOCK option was specified.

If a database snapshot can’t be created for any reason, DBCC CHECKDB attempts to use locks to obtain a transactionally consistent view of the database. First, it obtains a database-level exclusive lock so that it can perform the allocation consistency checks without any changes taking place. Offline consistency checks can’t be run on master or on tempdb because these databases can’t be exclusively locked. This means that allocation consistency checks are always skipped for tempdb (as was usually the case with SQL Server 2000, too). This also isn’t possible if the database is an Availability Group replica, in which case error 7934 is reported if the database snapshot creation fails.
Rather than wait for the exclusive lock indefinitely (or whatever the server lock timeout period has been set to), DBCC CHECKDB waits for 20 seconds (or the configured lock timeout value for the session) and then exits with the following error:

DBCC CHECKDB ('msdb') WITH TABLOCK;
GO
Msg 5030, Level 16, State 12, Line 1
The database could not be exclusively locked to perform the operation.
Msg 7926, Level 16, State 1, Line 1
Check statement aborted. The database could not be checked as a database snapshot could not be created and the database or table could not be locked. See Books Online for details of when this behavior is expected and what workarounds exist. Also see previous errors for more details.

If the lock was acquired after the allocation checks are completed, the exclusive lock is dropped and table-level share locks are acquired while the table-level logical consistency checks are performed. The same time-out applies to these table-level locks.
One way or another, DBCC CHECKDB obtains a transactionally consistent view of the database that it’s checking. After that, it can start processing the database.





Reference:Microsoft SQL Server 2012 Internals

Cannot specify a log file in a CREATE DATABASE statement without also specifying at least one data file.

Error Message:Msg 188, Level 15, State 1, Line 2Cannot specify a log file in a CREATE DATABASE statement without also specifying at least one data file.

Try this Solution:

Error of the Severity level 15 are generated by the user and can be resolved by the users. Just remove either the log file(.ldf) specification from Create database Script or specify at least one data file(.mdf).

Tempdb is skipped. You cannot run a query that requires Tempdb

tempdb is skipped. You cannot run a query that requires tempdb

You Might have applied a patch that required the database server to be rebooted during a scheduled outage. The application on the web server might have connections cached to the database, which were invalid at that point. In the .Net implementation of connections, they only support the statuses Open and Closed, and Broken . So it boils down to the connection trying to use resources that are no longer there, but that doesn't explain this specific message. 

Solution: At this point the solution is to restart IIS/Reboot the box. 

Procedures

To restart IIS using IIS Manager

1. In IIS Manager, right click the local computer, point to All Tasks, then click Restart IIS.

2. In the What do you want IIS to do list, click Restart Internet Services on computer name.

3. IIS attempts to stop all services before restarting. IIS waits up to five minutes for all services to stop. If the services cannotbe stopped within five minutes, all IIS services are terminated, and IIS restarts. In addition, clicking End now forces all IIS services to stop immediately, and IIS is restarted.

What is IIS?

Definition - What does Internet Information Services (IIS) mean?

Internet Information Services (IIS), formerly known as Internet Information Server, is a web server producted by Microsoft. IIS is used with Microsoft Windows OSs and is the Microsoft-centric competition to Apache, the most popular webserver used with Unix/Linux-based systems.
Techopedia explains Internet Information Services (IIS)

IIS was initially released for Windows NT and, along with ASP (Active-Server Pages), finally made a Windows-box a usable alternative for web-hosting. That being said, it was also noted for being completely wide-open out of the box and required significant configuration to be made secure. 

This changed with later releases, and IIS is now generally considered by many to be a stable and usable product. As of 2011, the most current version is IIS 7, which includes pretty much all modern features you'd expect to see in a webserver, including tight integration to ASP.NET. Though, as with any Microsoft vs Linux debate, some would argue that Apache is the only way to go.