09. Filesystems
- File
- named data
- that's all, really!
- Filesystem (logical level)
- organizing data on data storage with files:
- Identification (e. g. full path)
- Modes of usage (e. g. file read and write)
- Access rights
- Other file objects (directories, links etc.)
- Filesystem (physical level)
- organizing data on data storage with files:
- Naming and metadata
- File allocation
- Free space
Continuous files
If reading device positioning is actually slow, no need for speed optimization.
E. g.: magnetic band
- block № 000
- First file
- file name/size
- data
- block № 012
- Second file
- file name/size
- data
- Empty name / tail size
Metadata is written on the sheet of paper, file is selected by manual winding or by traversing all the records (read header, speed winding to the next header atc.)
Fixed-length metadata (directory) can be written at the start of the tape.
Writing to the file is marking the file record «old» and creating a new one:
- block № 000
- First file
- file name/size
- data
- block № 012
- Free space
- old file name/size
- data
- file name/size
- data
- Empty name / tail size
MT needs free space defragmentation (just by copying actual files to empty tape).
MT is useful for small number of files.
File allocation table
File is not continuous
TODO more plan