Computer Science Storage Media

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Questions and Answers

What type of storage is characterized as non-volatile and moderately fast in access time?

Cache storage

Primary storage

Secondary storage (correct)

Tertiary storage

Which of the following is true about tertiary storage?

It provides fast access time for active data.

It is the highest level in the storage hierarchy.

It is used for archival storage. (correct)

It is usually built for quick file retrieval.

When using fixed-length records, what is a potential problem that may occur?

Records cannot be accessed sequentially.

Records may not fit into memory properly.

Records cannot be deleted.

Records may cross block boundaries. (correct)

What is a method to handle deletion of records in a fixed-length record structure?

Link all free records on a free list. Signup and view all the answers

Which characteristic is true regarding variable-length records compared to fixed-length records?

They can store records of different sizes. Signup and view all the answers

In what scenario might fixed-length records complicate deletion?

Moving records after a deleted record to fill the gap. Signup and view all the answers

What type of database mapping stores records of only one fixed length in each file?

File-based database structure Signup and view all the answers

What is a common capacity range for magnetic tape in tertiary storage?

1 to 12 TB Signup and view all the answers

What is a characteristic of volatile storage?

Loses data when power is switched off Signup and view all the answers

Which factor is not typically considered when choosing a physical storage medium?

Storage media brand Signup and view all the answers

Which of the following is an example of primary storage?

Main Memory Signup and view all the answers

What distinguishes secondary storage from tertiary storage?

Secondary storage typically has faster data access than tertiary storage Signup and view all the answers

Which of the following describes variable-length records?

Record sizes can vary based on data content Signup and view all the answers

What is a key benefit of non-volatile storage?

Content remains intact even when power is lost Signup and view all the answers

Which tier of the storage hierarchy typically offers the lowest speed and access frequency?

Tertiary storage Signup and view all the answers

What does storage organization in main-memory databases primarily focus on?

Efficient data retrieval processes Signup and view all the answers

What is one method for handling the deletion of a record in fixed-length records?

Move the last record to the deleted record's position Signup and view all the answers

Which of the following describes a characteristic of variable-length records?

They can store multiple record types in a single file Signup and view all the answers

What is the purpose of the slotted-page structure in variable-length records?

To organize records without empty space between them Signup and view all the answers

Which term refers to the number of records that can be stored in a block?

Blocking Factor (Bfr) Signup and view all the answers

What type of information is typically found in the header of a slotted page structure?

Number of records entries and end of free space Signup and view all the answers

What can happen if a block is oversized in terms of its size?

It may transfer unnecessary data, leading to memory over-allocation Signup and view all the answers

How can null values be represented in variable-length records?

With a bitmap that indicates the presence of null values Signup and view all the answers

Which of the following is true about fixed-length records in a block?

The number of records remains constant across all blocks Signup and view all the answers

Study Notes

Physical Storage Media

Physical storage media can be categorized as volatile (loses data when power is off) or non-volatile (data persists even without power).
Non-volatile storage includes secondary and tertiary storage, as well as battery-backed up main memory.
The choice of storage media is influenced by:
- Speed of data access
- Cost per unit of data
- Reliability

Storage Hierarchy

Storage hierarchy categorizes media based on speed and volatility.
Primary storage (cache and main memory) is the fastest but volatile.
Secondary storage (flash memory, magnetic disks) is the next level, non-volatile with moderate access speed. It is also called online storage.
Tertiary storage (magnetic tape, optical storage) is the slowest level, non-volatile, and used for archival storage. It is also called offline storage.
Magnetic tape is a sequential access media with capacities ranging from 1 to 12 TB. It is used in jukeboxes for petabytes of storage.

File Organization

A database is mapped to files that are organized as a sequence of records stored in disk blocks.
Fixed-length records are a simple approach to record storage, where each record occupies a predefined amount of space.
Variable-length records provide flexibility in accommodating different record sizes.
In variable-length records, attributes are stored sequentially, and variable length attributes are represented using fixed-size offsets and lengths.
Null values in variable-length records are managed using a null-value bitmap.

Fixed-Length Records

In fixed-length records, a record is stored in contiguous bytes.
Deletion of a record can be done via:
- Moving records following the deleted record to fill the gap.
- Moving the last record to the deleted position.
- Maintaining a free list to track available space without moving records.

Variable-Length Records

Slotted page structure is commonly used to organize variable-length records within a block.
The page header contains information about the number of records, free space, and location of each record.
Records can be rearranged within the page to avoid empty space, with pointers pointing to header entries instead of directly to records.

Blocking

Blocking is the process of arranging records in blocks.
A block is a transfer unit between secondary and primary storage.
Block size impacts performance, with oversize blocks potentially transferring unnecessary data and undersize blocks causing frequent reads.
Blocking Factor represents the number of records within a block.

Fixed Blocking

In fixed blocking, the number of fixed length records in all blocks is consistent.
Fixed blocking ensures that the number of records in each block is the same, simplifying block access and reducing disk usage.

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Description

This quiz covers the types of physical storage media, including volatile and non-volatile categories. You'll learn about storage hierarchy, including primary, secondary, and tertiary storage, as well as factors that influence the choice of storage media. Test your knowledge on speed, cost, and reliability of various storage options.