SstFileManager class manages the physical SST file disk space utilization and deletion. It can be configured by the user in
Options::sst_file_manager. This class, even though declared in a public header file, is not extensible and the only way to allocate a new instance is by calling
SstFileManager object can be shared by multiple DB instances. The limits configured in the
SstFileManager would be shared by all the DBs.
SstFileManager provides various options to control and limit the disk space utilization of SST files in the DB. See Managing Disk Space Utilization for more details.
The other key functionality provided by
SstFileManager is slow deletion (a.k.a rate limited deletion). On SSDs, enabling slow deletion helps reduce the rate of TRIM commands to the SSD, thereby improving read/write latencies. See Slow Deletion for more details.