Backup

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Backup Recovery
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The world is a dangerous place...
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Backup strategy

• The design and implementation of a well-planned
  backup and recovery strategy takes time and can
  be very complex.
• Its often tempting to not waste time
  maintaining backup files and following procedures
• But if you dont have time to backup, how will
  you have time to put everything back together in
  the inevitable event of a disaster?

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Backup strategy

• Its the old pay me now, or pay me later
  situation. Either way, you have to pay...
• The point is to do assess the risks, costs, and
  benefits

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Backup strategy

• Risks arent easy to measure or assess, but many
  factors can be quantified, e.g.,
• frequency of required restores due to user error
  based on past data
• level and volume of usage
• others?

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Backup strategy

• Assessing the costs of implementation and
  maintenance are relatively straightforward.
• Equipment
• Consulting Services
• Staffing
• Training
• Etc.

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Backup strategy

• Sometimes the part is objectively assessing the
  benefit.
• Its easy to be mislead by
• vendor-based fear mongering
• the coolness factor (e.g., with this technology
  we can go 24x7!)
• Its hard to measure the true cost and therefore
  the benefit of avoiding
• downtime
• lost data

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Backup strategy

• this new technology could maximize availability,
  minimize performance impact during recovery, and
  minimize the risk of lost data, but do we need
  to?

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Disasters

• What are possible disasters?
• Building could be destroyed
• Statement failure (Server rolls the transaction
  back
• User-Process failure (PMON should clean up after
  failed program or procedure)
• User error/mistake (may require Import)
• Media failure (may require Import)
• Instance failure (SMON should clean up when new
  session created)
• Malicious attack (may require Import)

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Backup

• Whats a backup?
• A copy of a database that can be used in the
  event of an emergency.
• Recovery means to put things back like they were
  before the disaster.
• Whats a disaster?
• An event that creates an inability on an
  organizations part to provide critical business
  functions for some predetermined period of time."

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Backup

• Backups can be
• Logical (using Oracle export)
• Logical in that the read is independent of the
  location of the physical file
• Physical (using OS backup commands)
• Some combination

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Backup

• Backups can be done
• Offline
• Online
• Some combination
• It will depend on the requirements

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Backup

• Export utility
• 21 keywords and 23 parameters
• Oracle provides a GUI Recovery Manager (RMAN)
• Creates a binary export dump file
• Logical backups modes
• Full database
• specific user objects
• specific tables

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Import

• Logical backups are restored using the IMPORT
  utility
• reads data from dump file and executes embedded
  commands

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Data Guard Manager
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MySQL Backup Restore

• Backup SQL
• BACKUP TABLE tablename,tablename
• TO /path/to/backup/directory
• Restore SQL
• RESTORE TABLE tablename,tablename
• FROM /path/to/backup/directory

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MySQL Backup Restore

• Dump to textfile
• mysqldump database table gt textfile
• Example
• mysqldump practice emp gt employee.txt

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MySQL Backup Restore

• Load text file to the database
• Mysql database lt textfile
• Example
• mysql practice lt employee.txt