What is difference between file and filegroup in SQL Server?

What is file and filegroup backup in SQL Server?

When the database size and performance requirements make a full database backup impractical, you can create a file backup instead. A file backup contains all the data in one or more files (or filegroups). For more information about file backups, see Full File Backups (SQL Server) and Differential Backups (SQL Server).

What is a database filegroup?

A filegroup is a logical structure to group objects in a database. ... You can have multiple filegroups per database. One filegroup will be the primary, and all system tables are stored on it. Then, you add additional filegroups.

How many files are in a filegroup?

As a general rule of thumb, I recommend each filegroup having 2-4 data files, as this will give overall better I/O performance than a single data file. I've seen this over and over on client systems and you can see quite a few data points on the graph above reflecting that too.

What is the purpose of secondary data file?

Secondary data files are optional and can be used to spread data across multiple files/disks by putting each file on a different disk drive. SQL Server databases can have multiple data and log files, but only one primary data file.