Buffer underflow, also known as buffer underrun or buffer underwrite, is a threat to data that typically occurs when the temporary holding space during data transfer, the buffer, is fed at a lower rate than it is being read from. Opposite of a buffer overflow, this type of error arises when the flow of data from the original source, typically the hard drive, was interrupted long enough for the buffer to reach full capacity and empty itself. As a result, the writing action is stopped and the device receiving the data may be ruined.
The data buffer is a physical memory storage space that temporarily keeps information while it is in the process of being transferred to a new source. However, serious side effects can occur to devices or data when the buffer reading action encounters start-stop interruptions due to low speeds. The larger the buffer is, the less likely a buffer underflow will take place or that the transfer will be unsuccessful. For example, a buffer of 10 bits would protect against an interruption of up to 10 seconds before failing while a buffer of 60 bits would cover up to a minute.
A buffer underrun is often the result of issues such as a broken connection, an interrupted physical link, or high bandwidth competition. This is also a common problem observed when data is burned to a CD. Recording data to a CD must be performed in a real-time, nonstop process. Therefore, if the computer is not supplying data quickly enough and the signal is interrupted, the CD will not write the data properly.
How to fix buffer underflow:
- Increase the size of the buffer.
- Perform hard drive defragmentation before burning to an external device.
- Backup the data being transferred before writing.
- Avoid burning data onto a device over a network.
- Utilize hard drive scanning software to identify corrupted files before attempting an export.
- Check CPU and hard drive speed requirements to ensure there is enough RAM and hard disk space to complete the task.
- Make sure the device being written to functions properly.