Data Warehousing Backup Strategies

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Questions and Answers

What is the primary purpose of backing up data in a data warehouse?

To ensure data availability for recovery in the future (correct)

To free up storage space

To improve system performance

To reduce data complexity

What type of backup involves shutting down the database?

Cold backup (correct)

Partial backup

Hot backup

Online backup

What is the main advantage of partial backup?

It enables daily backups of parts of the database in a round-robin fashion (correct)

It is only used for small databases

It allows for daily backups of the entire database

It backs up the entire database at once

What factors affect the speed of processing backup and restore?

Hardware used, network bandwidth, server's I/O system, and backup software Signup and view all the answers

What type of backup is similar to hot backup?

Online backup Signup and view all the answers

What is the purpose of choosing the right hardware for backup?

To increase backup and restore speed Signup and view all the answers

What is the primary difference between hot and cold backups?

Hot backup requires the database to be up, while cold backup requires it to be shut down Signup and view all the answers

What is the main benefit of using complete backup?

It backs up the entire database at once Signup and view all the answers

What is the capacity of DLT tape media?

40 GB Signup and view all the answers

What is the primary function of a tape stacker?

To load multiple tapes into a single tape drive Signup and view all the answers

What is a factor to consider when selecting a tape medium?

The reliability of the tape medium Signup and view all the answers

How can standalone tape drives be connected to a server?

Directly to the server, as network available devices, or remotely to other machines Signup and view all the answers

What is a challenge in connecting tape drives to a data warehouse?

Ensuring sufficient bandwidth is available during data transfer Signup and view all the answers

What is the I/O rate of 8 mm tape media?

1 MB/s Signup and view all the answers

What is a consideration when upgrading a tape system?

The cost of upgrades to the tape system Signup and view all the answers

What is the capacity of 3490e tape media?

1.6 GB Signup and view all the answers

What is a common feature among tape silos, disk backups, and optical jukeboxes?

The ability to perform unattended backups Signup and view all the answers

What is the primary advantage of disk-to-disk backups?

Faster initial backups and restore Signup and view all the answers

What is the purpose of mirror breaking?

To create a temporary backup while the primary database is online Signup and view all the answers

What is a drawback of optical jukeboxes?

Slow write speed Signup and view all the answers

What is the primary purpose of software backups?

To assist in the backup process Signup and view all the answers

What is a characteristic of tape silos?

Ability to manage thousands of tapes Signup and view all the answers

What is a benefit of disk-to-disk backups?

Online copy of the latest backup Signup and view all the answers

What is a characteristic of optical media?

Long-life and reliability Signup and view all the answers

Study Notes

Data Warehousing Backup

A data warehouse is a complex system that requires a backup strategy to ensure data availability for recovery in the future.
Backup terminologies:
- Complete backup: backs up the entire database at once, including all files, control files, and journal files.
- Partial backup: does not create a complete backup of the database, useful for large databases.
- Cold backup: taken when the database is completely shut down.
- Hot backup: taken when the database engine is up and running, with varying requirements depending on the RDBMS.
- Online backup: similar to hot backup.

Hardware Backup

The choice of hardware affects the speed of processing backups and restores.
Hardware options:
- Tape technology
- Disk backups

Tape Technology

Tape media options:
- Capacity and I/O rates:
  - DLT: 40 GB, 3 MB/s
  - 3490e: 1.6 GB, 3 MB/s
  - 8 mm: 14 GB, 1 MB/s
- Other factors to consider:
  - Reliability of tape medium
  - Cost of tape medium per unit
  - Scalability
  - Cost of upgrades to tape system
  - Cost of tape medium per unit
  - Shelf life of tape medium
Standalone tape drives:
- Can be connected directly to the server, as network available devices, or remotely to other machines.
- Issues with connecting tape drives to a data warehouse, including node selection and optimal performance.
Tape stackers:
- Load multiple tapes into a single tape drive, allowing for unattended backups.
- Prices and capabilities vary.
Tape silos:
- Provide large storage capacities, storing and managing thousands of tapes.
- Can integrate multiple tape drives, with software and hardware for labeling and storing tapes.
- Often connected remotely over a network or dedicated link.

Disk Backups

Methods:
- Disk-to-disk backups
- Mirror breaking
Used in OLTP systems to minimize database downtime and maximize availability.
Disk-to-disk backups:
- Faster than tape backups
- Advantage of having an online copy of the latest backup
Mirror breaking:
- Have disks mirrored for resilience during the working day.
- Break out one of the mirror sets for backup.
- May require database shutdown to ensure consistency.

Optical Jukeboxes

Allow data to be stored near line.
Manage a large number of optical disks like a tape stacker or tape silo.
Drawback: slow write speed compared to disks.
Advantages: long-life and reliability, making them suitable for archiving.

Software Backups

Software tools are available to aid in the backup process.
These tools come as a package.

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Description

Learn about the importance of backing up data in a data warehouse and designing a backup strategy. Understand complete backup, incremental backup, and other backup terminologies.