the media rate, sector overhead time, head switch time, and cylinder switch time. Media rate Rate at which the drive can read bits from the surface of the media. Sector overhead time Additional time (bytes between sectors) needed for control structures and other information necessary to manage the drive, locate and validate data and perform other support functions. Head switch time Additional time required to electrically switch from one head to another, re-align the head with the track and begin reading; only applies to multi-head drive and is about 1 to 2 ms. Cylinder switch time Additional time required to move to the first track of the next cylinder and begin reading; the name cylinder is used because typically all the tracks of a drive with more than one head or data surface are read before moving the actuator. This time is typically about twice the track-to-track seek time. As of 2001, it was about 2 to 3 ms. Data transfer rate (read/write) can be measured by writing a large file to disk using special file generator tools, then reading back the file. According to vendor specifications sustained transfer rates up to 204MB/s are available. , a typical 7,200 RPM desktop HDD has a "disk-to-buffer" data transfer rate up to 1030 Mbit/s. This rate depends on the track location, so it will be higher on the outer zones (where there are more data sectors per track) and lower on the inner zones (where there are fewer data sectors per track); and is generally somewhat higher for 10,000 RPM drives. Floppy disk drives have sustained "disk-to-buffer" data transfer rates that are one or two orders of magnitude lower than that of HDDs. The sustained "disk-to-buffer" data transfer rates varies amongst families of Optical disk drives with the slowest 1x CDs at 1.23 Mbit/s floppy-like while a high performance 12x Blu-ray drive at 432 Mbit/s approaches the performance of HDDs. A current widely used standard for the "buffer-to-computer" interface is 3.0 Gbit/s SATA, which can send about 300 megabyte/s (10-bit encoding) from the buffer to the computer, and thus is still comfortably ahead of today's disk-to-buffer transfer rates. SSDs do not have the same internal limits of HDDs, so their internal and external transfer rates are often maximizing the capabilities of the drive-to-host interface. Effect of file system Transfer rate can be influenced by file system fragmentation and the layout of the