如何设置 NLog 最大文件大小？

Question

Is there any option/configuration in NLog to set the max log file size (for example 5MB)?

What I need is, that when the log file exceeds the max size (which I define), It will backup the old one (with a time stamp as file name), and start writing to a new one.

How can this be done? I would prefer some kind of build-in configuration, but if there is none can this be done safely manually without corrupting the log file?

Answer 1

You can set archiveNumbering="DateAndSequence" and archiveAboveSize="5000000"

<targets>
  <target xsi:type="File"
          archiveNumbering="DateAndSequence"
          archiveAboveSize="5000000"
          // other config
</targets>

See this note from here if you are using archiveAboveSize

archiveAboveSize - Size in bytes above which log files will be automatically archived. Long Caution: Enabling this option can considerably slow down your file logging in multi-process scenarios. If only one process is going to be writing to the file, consider setting ConcurrentWrites to false for maximum performance. Warning: combining this mode with Archive Numbering Date is not supported. Archive files are not merged. DateAndSequence will work

Answer 2

archiveAboveSize should do the trick. It sets the size (bytes) that will be used as a condition for archiving...
If you want to set archiveFileName to timestamp, ${ticks} can be used. But I would prefer combining date with sequence number, for better readability.

Answer 3

Since version 4.5.7 you can combine archiveAboveSize and archiveNumbering="Date" :

Date - Date style numbering. The date is formatted according to the value of archiveDateFormat.

• Warning: Before NLog ver. 4.5.7 then this would not work together with archiveAboveSize. Newer version will correctly merge into the
  existing file on archive.

https://github.com/nlog/NLog/wiki/File-target#size-based-file-archival