Since Windows 95 OSR (OEM [original equipment manufacturer] service release) 2, FAT32 system has been the mostly commonly used file system used by Windows 9x/Me users. Although this file system is not a revolution to earlier FAT file systems, it was indeed an important upgrade due to larger and larger hard disk sizes. The old FAT file system supports only up to 2GB logical drives with clusters each of 32KB size. FAT32 supports up to 2TB logical drives. If the logical drive is smaller than 256GB, FAT32 supports 4KB clusters. This means FAT32 supports far larger hard disks and wastes much less slack spaces. As an upgrade, FAT32 stores two backups of the boot sector in the first 32 sectors of the logical drive. Anyhow, because the use of linked lists in the implementation of the FAT32 file system, its performance is often lower than NTFS. For very large files, FAT32 is much slower than NTFS (Windows NT File System) when one of the files is randomly accessed. For directory containing many entries, FAT32 is also slower than NTFS.