Copyright (C) 2000-2012 |
GNU Info (fdutils.info)Mixed size sectorsMixed sector size (MSS) formats =============================== Using larger sectors has the disadvantage that the granularity is larger. For example, when using 4096 byte sectors, there is enough space to fit two sectors in a track of 12450 bytes raw capacity, but not three. However, the two sector format leaves plenty of space available (4132 bytes), in which smaller sectors would fit. For example, these 4142 raw bytes can be put to good use by filling them with a 2 KB sector (2048+62), plus an 1 KB sector (1024+62) and a 512 byte sector, leaving still 362 bytes for gaps. Mixed sector size formats take advantage of this by using sectors of several different sizes on a same track. This way, a maximum capacity of 12KB per track, distributed in one 8k sector and one 4k sector can be achieved. *Usage:* There is no known MS-DOS utility which can read basic MSS disks. Lilo is not yet able to boot from this kind of disks. *Performance:* As any format with larger sectors, the performance for small reads and writes is worse due to the larger granularity. *Interesting Formats:* density tot. cap. throughput media description 3 1/2 DD 880KB 28KB/s hd tracksize=11b mss 5 1/4 HD 1600KB 30KB/s hd tracksize=10KB mss 3 1/2 DD 880KB 28KB/s hd tracksize=11b mss 3 1/2 HD 1840KB 28KB/s hd tracksize=23b mss 3 1/2 HD 1920KB 30KB/s hd tracksize=12KB mss 3 1/2 ED 3680KB 56KB/s ed tracksize=23KB mss 3 1/2 ED 3840KB 60KB/s ed tracksize=24KB mss For MSS formats, the system figures out the most efficient repartition of sector sizes by itself. You do not need to describe the number of sectors and their size. For MSS disks, the capacity of one track is described directly, using the `tracksize' parameter. The `1920KB' and `3840KB' formats may be unreliable on some computers. |