CYS406 · Chapter 16

Data Security
At Rest, In Use, In Transit

The final chapter — why data is an organization's ultimate asset, the three states data can live in, how to encrypt disks/files/removable media, backup & RAID strategy, and how Data Loss Prevention (DLP) stops it from walking out the door.

Data States Data Security Technologies Disk / File / Media Encryption Backup & RAID SAN vs NAS DLP
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01 / Foundations

Why Data Security Matters

Data is the heart of any organization. Critical (business-critical) data is information that is important for business operations — identifying and classifying it is the first step in securing an organization's data.

Examples of Critical Data

Accounting files
Core financial records of the organization.
Databases / business data
Any business-related data held in databases.
OS files & purchased software
OS files that came with a computer, CDs, purchased software, etc.
Office documents
Important office documents, spreadsheets, etc.
Downloaded software
Software downloaded (purchased) from the Internet.
Contact information
Email address books and similar contact data.

Need for Data Security

Data is an organization's ultimate asset, and attackers are interested in it. If an organization's data is exposed or lost by any means, it can severely damage business and reputation.

⚠️ Causes of Data Loss
  • Loss/theft of laptops and mobile devices
  • Unauthorized data transfer to USB devices
  • Improper sensitive data categorization
  • Data theft by employees / external parties
💥 Business Effects
  • Brand damage and reputation loss
  • Competitive advantage loss / loss of customers
  • Market share loss / shareholder value erosion
  • Fines and civil penalties

The data at risk spans an organization's whole data landscape: Corporate Data, R&D, Customer Service/Customer Data, Sales, Contractor Data, Personally Identifiable Data (PII), HR/Legal, Finance, and Transaction Data — all of it moves across the network and needs to be protected wherever it lives.

🧠

Mnemonic — "LUID" causes data loss

"Lost Laptops, Unauthorized USBs, Improper labels, Data theft" → the four classic causes of data loss risk: Loss/theft of devices, Unauthorized transfer to USB, Improper sensitive-data categorization, Data theft by insiders/outsiders.

02 / Data States

The Three Critical States of Data

Data security involves applying various data security controls to prevent any intentional or unintentional act of data misuse, data destruction, and data modification. Every piece of data an organization holds is, at any moment, in exactly one of three states.

Data at Rest
Data in Use
Data in Transit
🧠

Mnemonic — RUT: Rest, Use, Transit

"Don't get stuck in a RUT"Rest (stored/inactive), Use (loaded in memory/RAM, actively being processed), Transit (moving across a network). Every byte of organizational data is always in one of these three states — that's the whole "three critical states of data" concept in one word.

Data at Rest vs Data in Use vs Data in Transit

Proper implementation of data security measures is required in each state to proactively enhance data security — a control that protects data at rest (like disk encryption) does nothing to protect the same data once it's in transit.

State Description Example Security Controls
Data at Rest Inactive data stored digitally at a physical location Customer bank balance stored in a database Data encryption, password protection, tokenization, data federation
Data in Use Data stored in memory, actively being processed Data stored in RAM Authentication techniques, tight access control, full memory encryption, strong identity management
Data in Transit Data traversing some means of communication An email being sent SSL and TLS, email encryption tools (PGP, S/MIME), firewall controls

In an organization's network, examples map onto real infrastructure: Data at Rest lives on workstations, laptops, and databases/repositories; Data in Use lives on the workstations and laptops actively processing it; Data in Transit moves through the firewall out to the Internet.

💡

One control does not cover all three states

Full disk encryption protects data at rest but is useless once that data is decrypted into RAM (in use) or sent over email (in transit). Always ask "which state is this data in right now?" before picking a control.

03 / Technologies

Data Security Technologies

Six core technology categories work together to secure data across its lifecycle and states.

Technology What It Does
Data Access Control Authenticates and authorizes users to access data
Data Encryption Protects information by transforming it so it cannot be read by an unauthorized party
Data Masking Protects information by obscuring specific areas of data with random characters or codes
Data Resilience and Backup Duplicates critical data for restore/recovery when a primary copy is lost or corrupted (accidentally or on purpose)
Data Destruction Destroys data so it cannot be recovered and used for wrong motives
Data Retention Stores data securely for compliance or business requirements
🧠

Mnemonic — "A MEDy Retention" (AMEDR)

"Access, Masking, Encryption, Destruction, Resilience, Retention"Access control, Masking, Encryption, Destruction, Resilience/backup, and Retention — the six data security technologies. Think of it as the full lifecycle: control who gets in, hide what they shouldn't see, scramble it, back it up, retain it as long as required, then destroy it securely when done.

04 / Encryption

Data Encryption Techniques

Data encryption for data at rest breaks down into three layers, from broadest to narrowest scope.

Disk Encryption

Full disk encryption is the encryption of all data in a disk except the master boot record (MBR).

File-level Encryption

Encryption occurs at a filesystem level; combined with a cryptographic algorithm, the encrypted data is extremely secure.

Removable Media Encryption

Prevents removable media devices — USB flash drives, portable hard disks, digital cameras, smartphones, tablets, etc. — from unauthorized access.

🧠

Mnemonic — Whole → Part → Portable

Think of it as zooming in: Disk encryption locks the whole drive, File encryption locks one file at a time, and Removable Media encryption locks whatever data walks out the door on a USB stick or phone.

Implementing Built-in Disk Encryption on Windows

1. Enabling Device Encryption

Start → Settings → Update & Security → Device Encryption → turn on the Device Encryption option.

2. Enabling Standard BitLocker Encryption

Sign in as Administrator → Start → Control Panel → System and Security → BitLocker Drive Encryption → Manage BitLocker → Turn on BitLocker.

Disk Encryption Tools

🔧 VeraCrypt

Software for establishing and maintaining an on-the-fly-encrypted volume (data storage device). On-the-fly encryption means data is automatically encrypted immediately before it's saved and decrypted immediately after it's loaded — without any user intervention.

Other tools mentioned: BitLocker Drive Encryption (Microsoft), FinalCrypt, Seqrite Encryption Manager, FileVault (Apple), Gilisoft Full Disk Encryption.

File-level Encryption

Windows provides the Encrypting File System (EFS) for built-in file system-level encryption.

File encryption tools: Advanced Encryption Package (file encryption software for Windows 10/8/7 using strong, proven algorithms), AxCrypt, idoo File Encryption, Cryptomator, Encrypto, AES Crypt.

Removable Media Encryption

To implement in Windows: Plug the removable media device into a USB port, then go to Start → Control Panel → System and Security → BitLocker Drive Encryption (Manage BitLocker).

🔧 GiliSoft USB Encryption

A solution for USB security that supports encrypting portable storage devices (external drives), and can divide an external drive into two parts after encryption: a secure area and a public area.

Other tools mentioned: idoo USB Encryption, Kakasoft USB Security, Rohos Mini Drive, McAfee File & Removable Media Protection, MFG's Removable Media Encryption.

05 / Backup

Data Backup

Data backup is the process of making a duplicate copy of critical data, such as physical (paper) and computer records. It's mainly used for two purposes: to reinstate a system to its normal working state after damage, or to recover data and information following data loss or corruption. A successful data backup strategy is necessary to avoid severe damage to an organization's assets.

Data Backup Strategy/Plan — 8 Steps

1

Identify the critical business data

Know what actually needs backing up before choosing how.

2

Select the backup media

Optical disks, portable hard drives/USB, or tape drives.

3

Select a backup technology

e.g. SAN, NAS, cloud, local.

4

Select the appropriate RAID levels

RAID 0, 1, 3, 5, 10, or 50 based on redundancy/performance needs.

5

Select an appropriate backup method

Hot (online), cold (offline), or warm (nearline).

6

Select the backup types

Full, differential, or incremental.

7

Choose the right backup solution

Pick a tool/vendor that fits the plan.

8

Conduct a recovery drill test

A backup you've never tested restoring is not a real backup.

🧠

Mnemonic — "I Must See RAID's Best Choice, Drilled" (8 steps)

Identify → Media → See(lect tech) → RAID levels → Backup method → Types → Choice(solution) → Drill — 8 words for 8 steps: Identify critical data, select Media, select technology, select RAID levels, select backup method, select backup Types, choose the right solution, and conduct a recovery Drill test.

Selecting the Backup Media

Data backups consume large amounts of storage space, so choose the backup media that best meets the organization's requirements — factors include capacity, cost, and speed.

Media Capacity Advantages Disadvantages
Optical disks (CD, DVD, Blu-ray) ~200 GB Affordable, easy to store and transport Several manual disk swaps needed (limited capacity); recording/verifying backup is slow
Portable hard drives / USB flash drives No limit Higher storage capacity than optical; ideal for home/small offices; faster recording More expensive than DVD backups; less recommended for small backups
Tape drives No limit Media for enterprise-level backups; easy to store and transport Expensive
06 / RAID

RAID — Redundant Array of Independent Disks

RAID is a method of combining multiple hard drives into a single unit and writing data across several disk drives, offering fault tolerance — if one drive fails, the system can continue operating. Placing data on RAID disks enables a balanced overlap of I/O operations, improving system performance, simplifying storage management, and protecting against data loss. RAID represents a portion of computer storage that can divide and replicate data among several drives, working as secondary storage.

RAID has six levels — RAID 0, 1, 3, 5, 10, and 50 — and all levels depend on three underlying storage techniques: Striping, Parity, and Mirroring.

🧠

Mnemonic — "013510 50" and "SPM"

The six RAID levels in slide order: 0, 1, 3, 5, 10, 50 — notice they're the same digits (0,1,3,5) then two combos (10 = 1+0, 50 = 5+0). The three building-block techniques spell SPM: Striping (split data across disks), Parity (error-correcting redundancy data), Mirroring (exact duplicate copies).

✅ Advantages of RAID
  • Hot-swapping/hot plugging — replace a failed drive without affecting network functionality
  • Disk striping improves read/write performance
  • Increased RAID parity check prevents a system crash or data loss
⚠️ Disadvantages of RAID
  • Not compatible with some hardware/software (e.g. system imaging programs)
  • Data lost if key drives fail one after another (e.g. RAID 5's parity drive can't recreate a first drive if a second drive also fails)
  • Cannot protect data and boost performance for all applications

RAID Levels Compared

Level Technique Min. Drives Redundancy? Key Notes
RAID 0 — Disk Striping Striping only 2 ❌ None Splits data into blocks written evenly across drives; improves I/O by spreading load; data recovery is not possible if a drive fails
RAID 1 — Disk Mirroring Mirroring only 2 ✅ Yes Multiple copies written to multiple drives simultaneously; if one drive fails, data recovery is possible
RAID 3 — Striping with Parity Byte-level striping + 1 dedicated parity drive 3+ (parity drive extra) ✅ Yes Data striped at byte level across drives; one drive per set holds parity; if a drive fails, data recovery/error correction uses the parity drive
RAID 5 — Block-Interleaved Distributed Parity Byte-level striping + distributed parity 3 ✅ Yes Data striped at byte level; parity distributed among all member drives (not one dedicated drive); writing is slow
RAID 10 — Striped & Mirrored (RAID 1+0) Striping (RAID 0) + Mirroring (RAID 1) 4 ✅ Yes Combines RAID 0 and RAID 1; same fault tolerance as RAID 1, same mirroring overhead as RAID 0; stripes data across mirrored pairs for max performance
RAID 50 — Mirroring & Striping across RAID levels (RAID 5+0) Striping (RAID 0) + distributed parity (RAID 5) 6 ✅ Yes (more fault-tolerant than RAID 5) More fault tolerant than RAID 5 but uses twice the parity overhead; a drive from each segment can fail and the array recovers — but >1 failure in a segment stops the array; offers the best reads/ writes and highest redundancy/performance of the group

RAID Storage Architecture — Core Components

RAID Controller

Manages an array of physical disk drives and presents them to the computer as logical units.

IDE, SATA, or SCSI Interface

Internal drives connect via these interfaces; connection to the server is also through one of these.

Multiport Memory Controller

Provides access to a memory bank and helps achieve high efficiency with random address accesses.

SDRAM

Dynamic RAM synchronized with the CPU clock speed.

Primary RAID Memory Cache

Used to write data in transition — a RAID system uses a cache to speed up I/O performance on the storage system.

nvSRAM / NAND Flash / Disk

nvSRAM is the fastest nonvolatile RAM (≈20 ns read/write); NAND Flash gives nonvolatile storage for the primary cache; the hardware presents the whole RAID to the host system as one single, large disk.

07 / Storage Networks

SAN vs NAS

Beyond a single machine's RAID array, organizations connect storage across the network using either a SAN or a NAS.

🖧 Storage Area Network (SAN)

A specialized, dedicated, discrete high-speed network that connects storage devices (disks, disk arrays, tapes, servers, etc.) with a high-speed I/O interconnect (Fiber Channel, SAS, Ethernet, etc.). Preferred in large enterprises for reliable data transfer and flexible scalability. Supports data archival, backup, restore, transfer, retrieval, migration, and mirroring between storage devices.

Three layers: the Communication Infrastructure Layer (physical connections to network devices), the Management Layer (organizes connections, storage elements, computer systems), and the Storage Layer (hosts the storage devices).

📁 Network Attached Storage (NAS)

A file-based data storage service and dedicated computer appliance shared over the network — a high-performance file server optimized for storing, retrieving, and serving files. NAS servers run proprietary or open-source OSes optimized for file serving.

Advantages of SAN

Storage consolidation

LAN-free and server-free data movement

Ease of data sharing

LAN-free and server-free backup

Improved backup and recovery

Highly available server clustering

Reliable, secure centralized data storage

Data integrity, decreased LAN load

High performance, low latency

Disaster tolerance

NAS — Advantages & Disadvantages

✅ Advantages
  • Users with different OSes can share files with no compatibility issues
  • A NAS can be connected to a LAN using plug-and-play
  • Minimal administration required, unlike Unix/NT file servers
⚠️ Disadvantages
  • Bandwidth-heavy applications significantly reduce network performance
  • Data transfer is inefficient — uses TCP/IP instead of a specialized data transfer protocol
🧠

Mnemonic — SAN = block, NAS = file

"SAN is a Storage-Area Network of raw disks; NAS is Network-Attached Storage of files." SAN feels like a private dedicated highway just for storage traffic (Fiber Channel); NAS is a file server plugged straight into your everyday LAN.

08 / Backup Methods

Backup Methods, Locations & Types

Selecting an Appropriate Backup Method

Select a backup method based on cost and ability, according to the organization's requirements.

Method Description Advantage Disadvantage
Hot Backup (Online) Backup while the application/database/system is running and available to users; used when downtime is not allowed Immediate data backup switch-over is possible Very expensive
Cold Backup (Offline) Backup while the application/database/system is shut down and unavailable; used when downtime is allowed and a full backup is required Least expensive Switching over the data backup requires additional time
Warm Backup (Nearline) A combination of both hot and cold backups Less expensive than hot; switch-over faster than cold but slower than hot Less accessible than hot backup
🧠

Mnemonic — Hot/Warm/Cold = Available/Between/Off

"Hot = running, Cold = off, Warm = in between" — exactly like food: hot backup happens while the system is live (expensive, instant switch-over), cold happens while it's shut down (cheap, slow switch-over), warm splits the difference.

Choosing the Backup Location

Onsite Data Backup

Storing backup data at onsite data storage only.
Advantage: easily accessed and restored; less expensive.
Disadvantage: greater data loss risk.

Offsite Data Backup

Storing backup data in remote locations in fire-proof, indestructible safes.
Advantage: secured from physical threats (fire, floods, etc.).
Disadvantage: problems with a regular backup schedule.

Cloud Data Backup

Storing backup data on storage provided by an online backup provider.
Advantages: encrypted and free from physical threats; accessible from anywhere.
Disadvantages: no direct control of the backup data; more time to back up.

Types of Backup

Full / Normal Data Backup

All system data is copied to the backup media.

Differential Data Backup

All data changed since the last full backup is copied to the backup media.

Incremental Data Backup

Only files changed or created after the last backup (of any type) are copied.

📘 Worked Example — a week of backups

Full backup: Sunday → 10GB baseline.
Differential path (each measured against Sunday's full backup): Monday 100MB, Tuesday 200MB, Wednesday 500MB — the differential backup keeps growing because it always captures everything changed since Sunday.
Incremental path (each measured against the previous backup): Monday 100MB, Tuesday 100MB, Wednesday 300MB — each incremental only captures what's new since yesterday's backup, so the size resets each day.

Type Advantages Disadvantages
Full Backup Restoration is fast Backup process is slow; high storage requirements
Differential Backup Faster than a full backup; restoration faster than incremental; reduced storage vs full Restoring is slower than full; slower than incremental
Incremental Backup Fastest backup method; least storage space of the three Slowest restore speed of the three
🧠

Mnemonic — Full/Diff/Incr trade-off is a see-saw

"Full = slow to back up, fast to restore. Incremental = fast to back up, slow to restore. Differential = the middle ground." Backup speed and restore speed are always opposite ends of the same see-saw across the three types.

Data Backup Tools

File History is a built-in Windows backup tool — it regularly backs up important folders like Desktop, Documents, Downloads, Music, Pictures, Videos, and parts of the AppData folder.

Other tools: Genie Backup Manager Pro, BullGuard Backup, NTI Backup Now EZ, Power2Go 13, Backup4all.

Data Recovery Tools

EaseUS Data Recovery Wizard can quickly retrieve lost files after deletion or emptying the recycle bin. Others: Recuva, Puran File Recovery, Glary Undelete, SoftPerfect File Recovery, Wise Data Recovery.

09 / Retention

Data Backup Retention

Data Retention
The process of storing and maintaining important information to meet compliance and business data archival requirements.
Data Retention Policy
A set of rules for preserving and maintaining data for operational or regulatory compliance requirements. Defines required retention periods per data type, and sets minimum standards for destroying certain information.

Steps for Developing a Data Retention Policy

1

Build a data retention policy development team

2

Understand applicable legal requirements

Determine the organization's applicable legal requirements.

3

Identify and classify the data

Determine what data is to be included in the retention policy.

4

Develop the data retention policy

5

Ensure all employees understand it

Make sure every employee understands the organization's data retention policy.

Data Retention Policy Best Practices (8)

Create a policy that fulfils legal and business requirements

Justify the reasons behind the policy details

Start with minimal requirements, add new ones as needed

Create a simple policy that's easy for employees to implement

Create different policies for different data types, per their legal/business impact

Retain customer/subscriber/user info only as long as necessary

Implement software to manage the data retention tasks

Classify data and decide if it should be archived or deleted

🧠

Mnemonic — "Justify, Minimal, Simple, Split, Necessary, Software, Sorted" + Legal

"Legal first, Justify it, keep it Minimal & Simple, Split by type, keep data only while Necessary, use Software, and get it Sorted (archive/delete)" — a retention policy must (1) meet Legal/business needs, (2) be Justified, (3) start Minimal, (4) stay Simple, (5) be Split per data type, (6) hold user data only while Necessary, (7) be run by Software tooling, and (8) end with data Sorted into archive-or-delete.

10 / DLP

Data Loss Prevention (DLP)

Data Loss Prevention (DLP) includes a set of software products and processes that do not allow users to send confidential corporate data outside the organization.

Organizations use DLP to:

🧠

Mnemonic — DLP's 5 jobs: "DMP-PM"

"Discover, Monitor, Protect, Prevent, Manage"Discover leak sources → Monitor those sources → Protect assets/resources → Prevent accidental disclosure → Manage resources with policy. Five verbs, five DLP jobs.

Types of DLP Solutions — By Data State

Notice how the three DLP solution types map exactly onto the three data states from Section 2.

💻 Endpoint DLP

Monitors and protects PC-based systems such as tablets and laptops. Used for preventing data leakage through clipboards, removable devices, and sharing applications. (Protects data on the device — a blend of "at rest" and "in use.")

🌐 Network DLP

Monitors, protects, and reports all data in transit. Installed at the "perimeter" of an organization's network; helps security professionals scan all data moving through ports and protocols within the organization.

🗄️ Storage DLP

Monitors and protects data at rest — data stored in an organization's data center infrastructure such as file servers, SharePoint, and databases. Identifies where sensitive information is stored and helps users determine whether it's stored securely.

🧠

Mnemonic — "END-NET-STORE" ties DLP to data states

Endpoint DLP ≈ In Use, Network DLP = In Transit, Storage DLP = At Rest. The three DLP flavors are just the three data states wearing different hats — remembering "RUT" (Rest, Use, Transit) from earlier instantly gives you all three DLP types too.

DLP Solutions — Examples

🔧 Windows Information Protection (WIP)

Has an endpoint DLP capability that helps protect local data at rest on endpoint devices. WIP can be configured to store business data only on approved devices / within approved applications.

🔧 MyDLP

Allows the user to monitor, inspect, and prevent all outgoing confidential data without any hassle.

Other DLP vendors: Symantec Data Loss Prevention, SecureTrust Data Loss Prevention, McAfee Total Protection, Check Point Data Loss Prevention, Digital Guardian Endpoint DLP.

Best Practices for a Successful DLP Implementation

1

Identify the main objective of DLP

2

Identify sensitive data for protection

3

Evaluate available DLP vendors

4

Ensure product compatibility

The selected DLP product must be compatible and support the required data types and data stores.

5

Identify roles and responsibilities

For individuals implementing the DLP solution.

6

Implement with a minimal base

Reduce false positives, then gradually enhance the base by identifying sensitive data.

7

Enhance the DLP policies

Support effective DLP operations and eliminate false positives.

11 / Exam Prep

Exam Tips & Tricks

💡

Three data states = RUT

Data at Rest (stored), Data in Use (in memory/RAM), Data in Transit (moving over the network). Every control question is really asking "which state, and which control fits it?"

Encryption controls per state

At Rest → data encryption, tokenization. In Use → memory encryption, strong identity management. In Transit → SSL/TLS, PGP/S/MIME, firewalls.

⚠️

RAID 0 has NO redundancy

RAID 0 is striping only — it boosts speed but a single drive failure loses everything. Don't confuse it with RAID 1 (mirroring = redundancy).

🔑

Differential vs Incremental — always vs last full

Differential always backs up everything changed since the last full backup (grows daily). Incremental only backs up what changed since the last backup of any type (resets daily, fastest to back up, slowest to restore).

📋

DLP types mirror data states

Endpoint DLP (device-level), Network DLP (in transit / perimeter), Storage DLP (at rest / data center). Same "Rest/Use/Transit" logic reused for DLP.

🌐

SAN = block storage network, NAS = file server on the LAN

SAN uses Fiber Channel/SAS for high-speed dedicated storage traffic; NAS is a plug-and-play file server that rides on ordinary TCP/IP.

🗂️

RAID minimum drive counts

RAID 0/1 need 2 drives, RAID 5 needs 3, RAID 10 needs 4, RAID 50 needs 6 — these numbers are a classic exam trap.

🔥

Hot/Warm/Cold backup = system state, not temperature

Hot = system running (expensive, instant), Cold = system shut down (cheap, slow switch-over), Warm = mix of both.

12 / Cheat Sheet

Quick Reference — Everything at a Glance

Topic Key Point
Business-critical data Info important for business ops — accounting files, databases, OS files, office docs, downloaded software, contact info
Causes of data loss Lost/stolen laptops, unauthorized USB transfer, improper categorization, insider/external theft
Effects of data loss Brand/reputation damage, lost competitive advantage/customers, market share loss, fines/penalties
Data security Applying controls to prevent misuse, destruction, and modification of data
Three critical states of data Data at Rest, Data in Use, Data in Transit ("RUT")
Data at Rest example / controls Bank balance in a database / encryption, password protection, tokenization, data federation
Data in Use example / controls Data in RAM / authentication, tight access control, full memory encryption, strong identity mgmt
Data in Transit example / controls An email being sent / SSL & TLS, PGP or S/MIME, firewall controls
Data security technologies (6) Access Control, Encryption, Masking, Resilience & Backup, Destruction, Retention
Disk encryption Encrypts all data on a disk except the MBR (e.g. BitLocker, VeraCrypt, FileVault)
File-level encryption Encrypts at the filesystem level (Windows EFS; AxCrypt, AES Crypt, Cryptomator)
Removable media encryption Protects USB drives, portable HDDs, phones, tablets, etc. (BitLocker, GiliSoft USB Encryption)
On-the-fly encryption (VeraCrypt) Auto-encrypts before save, auto-decrypts after load — no user intervention
Data backup — purpose Reinstate a damaged system, or recover lost/corrupted data
8-step backup strategy Identify data → media → technology → RAID level → method → type → solution → recovery drill test
Backup media types Optical disks (~200GB, cheap, slow), Portable HDD/USB (no limit, faster, pricier), Tape (no limit, enterprise, expensive)
RAID definition Combines multiple drives into one unit; offers fault tolerance if a drive fails
RAID storage techniques Striping, Parity, Mirroring
RAID 0 Striping only, 2 drives min, NO redundancy, no recovery if a drive fails
RAID 1 Mirroring, 2 drives min, redundant — recovery possible if one drive fails
RAID 3 Byte-level striping + 1 dedicated parity drive
RAID 5 Byte-level striping + parity distributed across all drives, 3 drives min, slower writes
RAID 10 (1+0) Striping + mirroring, 4 drives min, RAID 1 fault tolerance + RAID 0 performance
RAID 50 (5+0) Striping + distributed parity across RAID 5 sets, 6 drives min, most fault-tolerant/best perf of the six
RAID advantages Hot-swapping, improved read/write via striping, parity check prevents crash/data loss
RAID disadvantages Hardware/software incompatibility risk, cascading drive failures lose data, doesn't help every app
SAN Dedicated high-speed network of storage devices (Fiber Channel/SAS); block-level; large-enterprise scale
NAS File-based storage appliance on the LAN; plug-and-play; uses TCP/IP (less efficient than SAN)
Hot / Cold / Warm backup Hot = system running (expensive, instant); Cold = system off (cheap, slow); Warm = combo of both
Onsite / Offsite / Cloud backup location Onsite = fast access, higher loss risk; Offsite = fire/flood-safe, scheduling issues; Cloud = encrypted & anywhere access, no direct control
Full backup Copies all data; fast restore, slow/large backup
Differential backup Copies everything changed since the last FULL backup; grows over time
Incremental backup Copies only what changed since the last backup (any type); fastest backup, slowest restore
Data retention Storing/maintaining info for compliance and business archival requirements
Data retention policy Rules for preserving data; defines retention periods and destruction standards per data type
Data Loss Prevention (DLP) Software/processes stopping confidential data from leaving the organization
DLP goals Discover leaks, Monitor sources, Protect assets, Prevent accidental disclosure, Manage resources
Endpoint DLP Protects PC-based systems (laptops, tablets); blocks leakage via clipboard, removable devices, sharing apps
Network DLP Protects data in transit at the network perimeter; scans ports/protocols
Storage DLP Protects data at rest in file servers, SharePoint, databases
Windows Information Protection (WIP) Endpoint DLP that restricts business data to approved devices/apps