File Management Flashcards
File management separates :
Design and implementation
What is a file ?
A file is a named collection of related information that is recorded on a secondary storage
What are the attributes of a file ?
Name Identifier Location Size Protection mode ( giving permissions) Times creation Access modification
What are the file operations
Create
Read
Update
Delete
How are files organized
Usually into directories with similar attributes and operations
Explain Mounting
When a file system on a storage device is mounted at a point in the existing file system
Features of the Linux file system
An everything is a file approach
Tree like structure
What does everything is a file mean :
Regular files : sequence of bytes Directories: name/inode association lists Special files: peripheral device Links: locations of other files Pipes:buffers between processes Symbolic links: names of other files
What is the magnetic disk made of ?
spinning platters over which hovers a head attached to a movable arm
How is a platter organized
A platter is divided into circular tracks
what is a platters track divided into?
sectors
What is a magnetic disks cylindermade up of?
The tracks at one arm position
How does a magnetic disk read/write?
by moving the arm to the required cylinder and using a head to sense/change the
magnetism of a sector
what is a solid state disk made of ?
controller(Microprocessor) buffer memory (Conventional Memory) flash memory(Easily Deteled)
Example of a typical solid state disks
ARM controller, 256Kb buffer 128Mb flash 4Kb pages 256Kb block size.
How is an SSD read ?
copying a flash memory page into the buffer
reading data from the page in the buffer
What actions may write on a solid disc?
copying a memory block into the buffer
erasing the block in the flash memory
modifying the block in the buffer
writing the block from the buffer to the flash memory
What can increase the lifetime of an SSD?
dynamic wear-levelling
static wear-levelling
What does dynamic wearleveling do?
writes new data to the least-recently-used block so cold data is not moved
What does static wear-levelling do?
it additionally periodically moves existing data to the least-recently-used block (cold data is moved)
