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183 lines
6.5 KiB
ReStructuredText
Backups
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*******
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Backups are a critical part of preserving an organization's
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information. RAID, clustering and other real-time copies of
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data do not help when the data is deleted, the buildings containing
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these live sources are compromised by weather, human intervention,
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or facilities failures.
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Could the organization survive if part or all of its information
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were lost?
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Remember, RAID is not a backup solution.
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RAID protects against the loss of individual drives, but if data gets corrupted
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or deleted, RAID will replicate that corruption across all RAID stripes.
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Making backups on separate media is the best way to protect yourself against
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both "hard" and "soft" data loss.
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Designing a backup policy
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=========================
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Operations needs to work with organizational leaders to develop a
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backup policy that protects the organization's information while
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balancing cost and other factors important to the organization.
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Operations engineers need to be able to understand organizational
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needs in order to evaluate backup solutions, strategies, and current
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best practices. They must then translate this knowledge into
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recommended solutions which management can use to make a sound
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business decision. The ability to assemble a cohesive plan, including
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a cost-benefit analysis of available options, can help the organization
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make the right decision for the business on an appropriate backup
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policy.
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Deciding what to backup
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-----------------------
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Consider cost, time, and staff resources when deciding what to
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backup. Does it make sense to backup every client hard drive when
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a system can be re-imaged over the network? Does the configuration
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management solution maintain client customizations? If so, operations
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may not need to backup the operating system on clients and can focus
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on user data. Ideally, the goal is not to restore clients starting at
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the operating system level.
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Where is organizational data stored? Is data local on each client or
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does the organization use a file server? Do users actually
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store their data on the file server? Some users have had bad experiences
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using the network and move all of their data locally, or refuse to
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store anything on the server in case the network becomes unavailable.
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If users travel frequently, they may store all of their data
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on a laptop. This poses additional backup challenges when laptops
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are not always on the organization's network to talk to the backup
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server.
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Some organizations perform incremental backups on all clients to
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protect against users who decide where best to store their data.
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What about data stored on servers? Do all servers need to be backed
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up? What is the available backup window and will the organization's
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network push enough data to a backup server to fit within that
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window? How will taking the backup affect each application's
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performance?
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Ultimately, deciding what to backup is a business decision. What
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information is critical to the business and how much is the
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organization willing to invest to protect that information? There
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may also be laws requiring the organization to retain certain data
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that will influence this decision.
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When not to backup
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^^^^^^^^^^^^^^^^^^
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.. TODO:: restoring? what not to backup, regulations on same, how to store them (PCI)
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Retention periods
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-----------------
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Is there a risk to having a long retention period?
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.. TODO:: The idea of such a risk may not be immediately clear to a beginning ops person.
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What is the cost to retain backups for a 30-days, 6-months, or 1 year?
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Is there a business requirement for keeping backups for a specific length of time?
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Are there laws for maintaining electronic records for a specific period of
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time?
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If the organization is required to adhere to Freedom of
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Information Act (FOIA) law, sometimes long retention periods are a
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detriment. FOIA requests can cover any kind of data including
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individual emails on a specific subject. If the information doesn't
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benefit the organization, then it might be a liability due to
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labor-intensive searches through ancient backups.
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.. TODO:: How does FOIA affect what information an organization needs to have available? Assume the reader is a civilian and doesn't know how FOIA affects an organization.
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Offsite backups
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---------------
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How sensitive is the organization's information? Storing a copy
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of the organization's crown jewels in an insecure location can
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expose the organization to loss, unauthorized modification, or
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theft of intellectual property.
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Is the organization required to encrypt offsite data?
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Does the organization have a second geographically distributed
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location that could house an off-site backup of the organization's
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information?
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Designing a Backup System
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=========================
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Backup type and frequency
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-------------------------
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What kind of information does the organization rely on to do
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business? Do hourly changes need to be captured or can the
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organization survive with backups every 12-hours or once per day?
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* Full backups
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* Incremental backups
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* Replication
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* Snapshots
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* Bare-metal restore vs data only
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* online/offline
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.. TODO:: media -- should someone address the state of backup media? Some places are still doing tape. What about orgs who rely on standalone consumer-grade disks for client backups (e.g. Time Machine)? Risks, cost to maintain.
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Cost of backups
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---------------
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What is the cost of not doing backups?
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Verification
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============
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Test backups. If data cannot be restored then what was the
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point of backing it up in the first place.
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Recovery testing
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----------------
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How long does it take to restore the largest backup set?
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Integrity of backups
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--------------------
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Completeness of backups
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-----------------------
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Security implications
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=====================
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.. TODO:: Using backups to restore to a known "good" state after an incident just serves to put the machine in a known vulnerable state (security hole that was exploited is now back in operation)
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.. TODO:: can be used to restore system state that can be useful in a post mortem after an incident (say the attacker covered their tracks but backups were able to capture a rootkit before it was removed or before logs were tampered with)
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Recovery basics
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===============
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Secure data destruction
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=======================
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Information Lifecycle Management in relation to backups
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========================================================
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Main goal of backups is restore system state including data in case of issues and ILM, have data available for functional
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reasons other than uptime.
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Main items to cover in this chapter are:
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Archiving
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---------
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Data replication
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----------------
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