Operating System Role in Buffer Management
A person can manage the database buffer by using any of two approaches:
a) The database system reserves a part of the main memory to serve as a buffer, rather than the operating system managing it.
b) The database system implements its buffer within the bounds of the virtual memory provided by the operating system.
The operating system reserves space on disk for storing the virtual memory pages that are currently not present in the main memory, this space is called ‘swap space’.
Fuzzy Checkpointing :
The checkpointing technique requires that all updates to the database should temporarily be suspended while the checkpoint is in progress.
If the number of pages in the buffer is large, then a checkpoint may take a long time to complete, which can result in an unacceptable interruption in the processing of the transactions.
To avoid such interruptions, the checkpointing technique can be changed to permit updates to start once the checkpoint record has been written, but before the changed buffer blocks are written to the disk.
Therefore the checkpoint generated is a fuzzy checkpoint.
Reference Link