As we know that the Main
Memory Stores the data in a Temporary Manner means all the data will be loss
when the Power switched off. And all the data will be loss when the power goes
switched off. So that we uses the
Secondary Storage devices those are used for Storing the data in a permanently. Secondary storage
devices are those devices whose memory is nonvolatile, meaning, the stored data
will be intact even if the system is turned off. Here are a few things worth
noting about secondary storage.
·
Secondary storage is
also called auxiliary storage.
·
Secondary storage is
less expensive when compared to primary memory like RAMs.
·
The speed of the
secondary storage is also lesser than that of primary storage.
·
Hence, the data which is
less frequently accessed is kept in the secondary storage.
·
A few examples are
magnetic disks, magnetic tapes, removable thumb drives etc.
Hard disk drive performance characteristics
Access time refers to how fast the disk or memory
can locate and begin retrieving (accessing) a specific piece of information or
transfer data to the CPU. A low access time indicates a fast hard drive. Access
time is measured in milliseconds.
- Seek time: The seek time of a hard disk measures the amount of time required for the read/write heads to move between tracks over the surfaces of the platters
- Rotation latency is the average time for the sector being accessed to rotate into position under a head, after a completed seek. It is easily calculated from the spindle speed, being the time for half a rotation. A drive’s average access time is the interval between the time a request for data is made by the system and the time the data is available from the drive.
- BPI defines how many bits can be written onto one inch of a track on a disk surface.
- TPIThe key media recording parameters relating to density per platter are Tracks Per Inch (TPI)
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