Guidelines for data files and transaction logs

This topic lists the recommended sizes for data file and transaction logs.

In this topic:

MSQL Server/Server Express

This section lists the recommended data file sizes for MS SQL Server and MS SQL Server Express users.

Based on the number of users, we suggest the following guidelines for data files and transaction logs. Your needs may be different from those shown in the table below.

Number of Users	Number of Data Files	Size of Each Data File	Number of Log Files	Size of Each Log File
Up to 15	3	50MB	3	50MB
Between 15 and 50	3	300MB	3	300MB
Between 51 and 100	5	300MB	5	300MB
Between 101 and 300	7	500MB	5	500MB
>300	7	800MB	6	500MB

Transaction log backups are essential. After a transaction is backed up, Microsoft SQL Server and Microsoft SQL Server Express databases automatically truncate the inactive portion of the transaction log. This inactive portion contains completed transactions and is no longer used during the recovery process. The basic advantage comes with the fact that Microsoft SQL Server reuses this truncated, inactive space in the transaction log instead of allowing the transaction log to continue to grow and use more space. This is a huge plus from a performance standpoint.

Allowing files to grow automatically can cause fragmentation of those files if a large number of files share the same disk. Therefore, it is recommended that files or file groups be created on as many different available local physical disks as possible. Place objects that compete heavily for space in different file groups.

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Oracle schema

This section lists the recommended data file sizes for Oracle schema users.

Based on the number of users, we suggest the following guidelines for data files. Your needs may be different from those shown in the table below.

Number of Users	Number of Data Files	Size of Each Data File
Up to 15	3	50MB
Between 15 and 50	3	300MB
Between 51 and 100	5	300MB
Between 101 and 300	7	500MB
>300	7	800MB

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