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FatFs R0.13b, released April 7, 2018

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Christopher Williams
2018-04-14 23:23:25 -07:00
parent 2a5ed95231
commit 9c7d461c41
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documents/doc/mkfs.html
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@@ -59,9 +59,9 @@ FRESULT f_mkfs (
<h4>Description</h4>
<p>The FAT sub-type, FAT12/FAT16/FAT32, of FAT volume except exFAT is determined by only number of clusters on the volume and nothing else, according to the FAT specification issued by Microsoft. Thus the FAT sub-type of created volume depends on the volume size and the cluster size. In case of the combination of FAT type and cluter size specified by argument cannot be valid on the volume, the function will fail with <tt>FR_MKFS_ABORTED</tt>. The minimum drive size is 128 sectors with <tt>FM_SFD</tt> option.</p>
<p>The allocation unit, also called <em>cluster</em>, is a unit of disk space allocation for files. When the size of allocation unit is 32768 bytes, a file with 100 bytes in size occupies 32768 bytes of disk space. The space efficiency of disk usage gets worse as increasing size of allocation unit, but, on the other hand, the read/write performance increases as the size of allocation unit. Therefore the size of allocation unit is a trade-off between space efficiency and performance. For the large storages in GB order, 32768 bytes or larger (this is automatically selected by default) is recommended for most case unless extremely many small files are created on a volume.</p>
<p>There are two disk partitioning formats, FDISK and SFD. The FDISK format is usually used for harddisk, memory card and U disk. It can divide a physical drive into one or more partitions with a partition table on the MBR (maser boot record, the first sector of the physical drive). The SFD (super-floppy disk) format is non-partitioned disk format. The FAT volume starts at the first sector of the physical drive without any disk partitioning. It is usually used for floppy disk, optical disk and most super-floppy media. Some systems support only either one of the two disk formats and the other is not supported.</p>
<p>When the logical drive to be formatted is bound to a physical drive and <tt>FM_SFD</tt> is not specified, a primary partition occupies whole drive space is created and then the FAT volume is created in it. When <tt>FM_SFD</tt> is specified, the FAT volume occupies from the first sector of the physical drive is created without partitioning.</p>
<p>When the logical drive to be formatted is bound to a specific partition (1-4) by support of multiple partition (<tt><a href="config.html#multi_partition">FF_MULTI_PARTITION</a> == 1</tt>) the FAT volume is created into the partition and <tt>FM_SFD</tt> flag is ignored. The physical drive needs to be partitioned with <tt>f_fdisk</tt> function or any other partitioning tools prior to create the FAT volume with this function.</p>
<p>There are three disk partitioning formats, FDISK, SFD and GPT. The FDISK format is usually used for harddisk, memory card and U disk. It can divide a physical drive into one or more partitions with a partition table on the MBR (maser boot record, the first sector of the physical drive). The SFD (super-floppy disk) is non-partitioned disk format. The FAT volume starts at the first sector of the physical drive without any disk partitioning. It is usually used for floppy disk, optical disk and most super-floppy media. Some systems support only either one of the two disk formats and the other is not supported. The GPT (GUID Partition Table) is a newly defined format for large storage devices. FatFs does not support the storages with GPT.</p>
<p>When the logical drive to be formatted is bound to a physical drive and <tt>FM_SFD</tt> is not specified, a primary partition occupies whole drive space is created in FDISK format, and then the FAT volume is created in the partition. When <tt>FM_SFD</tt> is specified, the FAT volume occupies from the first sector of the physical drive is created in SFD format.</p>
<p>When the logical drive to be formatted is bound to a specific partition (1-4) by support of multiple partition (<tt><a href="config.html#multi_partition">FF_MULTI_PARTITION</a> == 1</tt>), the FAT volume is created on the partition and <tt>FM_SFD</tt> flag is ignored. The physical drive needs to be partitioned with <tt>f_fdisk</tt> function or any other partitioning tools prior to create the FAT volume with this function.</p>
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