You have scheduled your backups to a Shared Location or Network Path. Your backup was running fine, one fine day you suddenly come across an error saying "A nonrecoverable I/O error occurred on file "" 64(The specified network name is no longer available.)."

When you check for more information in logs you will find more description such as

You are working on some operations say reporting building or may be a folder creation in SSRS Report Manager and when you say ok you are hit with the below error.

"The permissions granted to user '' are insufficient for performing this operation. (rsAccessDenied)"

You have installed SQL Server Reporting Services may be 2008, 2008R2 or 2012. You are a domain user and you are local Administrator on the machine in which you have installed and configured reporting Services. You open your browser and type in the ReportManager URL ex http://machineName/Reports, you are hit with below error.

"User 'Domain\Username' does not have required permissions. Verify that sufficient permissions have been granted and Windows User Account Control (UAC) restrictions have been addressed."

A simple answer to considerations for a high Performance database is "It Depends"
Yes, Indeed it depends. let me elaborate some of the points.

What do you mean by High Performance Database System?
The data retrival time to be very less?
Processing of data at a faster pace?
Minimal usage of system resources and provide more performance
Multi Threading
Multi Tasking
Multi Processing
and the list goes on.

When you have configured the AlwaysOn High Avaiability feature of SQL Server 2012 on your machines, You may find the below critical and warning messages in dashboard.

DBCC CHECKDB is one of the powerful DBCC command. It Checks the logical and physical integrity of all the objects in the specified database.

However, when you try to run the DBCC CHECKDB, you might come across a error "A database snapshot cannot be created because it failed to start." when checked further, there might be error as below.

Today I had a series of Job Failures and the only common error I could see in my logs was "Named Pipes Provider: Could not open a connection to SQL Server [53]"

After investigating, it was discovered that, there was a network connectivity breakdown. Re-Running all of my Job was successful. In general, this error is issued when you are running a SSIS Package or a SQL Server Agent Job, and during execution, the connectivity to server is lost.

How many times you have come across the situation where the Database Owner for user databases on your server is not consistent and different databases have different owner. This is not mandatory to have a single user as DBOwner for all databases though. There might be scenarios where a developer or tester or any other person has created database and he is the owner for it and he has left the organization now. Such as there can be various scenarios where the database is owned by different users.

When you try to open the SQL Server Reporting Services Report Manager, you might get  the error saying "The report server has encountered a configuration error. See the report server log files for more information. (rsServerConfigurationError)".

When you go and check for the Error Logs you might find an error saying "Access to the path 'C:\Program Files\Microsoft SQL Server\MSSQL.4\Reporting Services\ReportServer\RSReportServer.config' is denied." Note the path may vary as per your installation, but error would be similar.

When you try to start SQL Server Analysis Service which is in stopped state, you might come across the below error.