Backup Assessment

How does disaster recovery work?

It uses off-site or cloud backups to restore systems and data after a disaster or total loss.

How does fault tolerance work?

It uses duplicate hardware or software components so if one fails, others continue running without stopping the service.

What is a backup?

A backup is a copy of data stored safely to restore it if it's lost, deleted, or corrupted.

What is a real-life example of disaster recovery?

Like a spare house key hidden outside—you use it after losing the original key in a crisis.

What is a real-life example of fault tolerance?

Like a car with two engines—if one stops, the second keeps the car running.

What is disaster recovery?

Disaster recovery is restoring data after a major failure like fire, flood, or cyberattack using backup copies.

What is fault tolerance?

A system's ability to keep running without data loss even if one part fails, using redundancy like RAID or load balancers.

Why do we need backup?

To protect data from hardware failures, human errors, cyberattacks, natural disasters, or software issues.

Advantages of full backup

It's easiest to restore since all data is in one place and only needs one restore session.

Disadvantages of full backup

It takes the most time and storage space, even copying unchanged files every time.

Example of differential backup

Like updating one sticky note daily with all changes since Monday.

Example of incremental backup

Like saving a journal: Monday you save the book, Tuesday just new pages, and so on.

How differential backup works day by day

Tuesday: changes since Monday. Wednesday: still since Monday. Data grows each day.

How differential restore works

You need only the full backup and the latest differential backup to restore.

How incremental backup works day by day

Monday: full backup. Tuesday-Friday: only changed or new files each day are backed up separately.

Key differences between incremental and differential backup

Incremental saves changes since the last backup; differential saves from the last full backup. Incremental is faster daily but slower to restore. Differential is slower daily but faster to restore.

Main advantage of incremental backup

It's fast and uses minimal storage since it saves only small daily changes.

Real-life example of differential restore

After a crash on Saturday, restore Monday's full and Friday's differential backup.

Real-life example of incremental restore

Like loading a game: full save + daily progress; missing one and it won't load fully.

What is a differential backup

It backs up all changes made since the last full backup—not just from the last day.

What is a full backup

A full backup copies all data every time it runs, storing everything into one file or tape.

What is incremental backup

It backs up only the files changed since the last backup (full or incremental), saving time and space.

What is incremental restore

To restore, you need the full backup plus all incremental backups in the correct order.

When to use full backup

Use it for small to medium datasets where storage and speed aren't a concern, and quick recovery is needed.

Why incremental restore is slower

It requires multiple restore steps, and missing or corrupt sets can cause failure.

What is Backup Retention?

Backup Retention is the policy that defines how long backup data is stored before it is deleted or overwritten. Simple Example: It’s like deciding how long to keep photos in your phone—1 month, 1 year, or forever.

Why is Retention Important in Backup?

Retention is important because it ensures old backups are available when needed. It protects against data loss, helps meet legal requirements, manages storage space, and allows recovery from ransomware attacks.

How does Backup Retention help with Data Loss Protection?

Retention keeps old backups so if something is accidentally deleted or if a system fails, you can restore the data from an earlier saved point. Simple Example: If you saved a backup on July 1st and your system crashes on July 15th, you can recover the July 1st backup because of retention.

How does Backup Retention help with Compliance?

Some industries have legal rules requiring companies to keep backups for a certain period. Simple Example: A hospital may need to keep patient data backups for 5 years to comply with healthcare regulations.

How does Backup Retention manage Storage Space?

Retention policies automatically delete old backups after a set time to save storage space. Simple Example: If you set daily backups for 7 days, backups older than 7 days get deleted automatically.

How does Backup Retention help during Ransomware Attacks?

Retention allows you to restore data from a time before the ransomware attack happened. Simple Example: If ransomware encrypts your files on July 20th, you can restore a July 10th backup if it is still retained.

Real-World Example of Backup Retention Policy

Imagine you’re an IT Admin: You set daily backups of company data and configure a 30-day retention policy. Each day’s backup is kept for 30 days. After 30 days, the oldest backups are automatically deleted.

What is a Physical Server?

A Physical Server is a real, tangible computer (hardware) located in a data center or server room.

It contains CPU, RAM, hard drives, and network cards—just like a personal computer but much more powerful.

It usually runs one operating system directly on the hardware.

Real-World Example: Imagine a big computer tower in an office running company email services. This tower is the physical server.

What is a Virtual Machine (VM)?

A Virtual Machine (VM) is a software-based computer that runs inside a physical server using virtualization software like VMware, Hyper-V, or VirtualBox.

Each VM behaves like a real computer, with its own OS, CPU, RAM, and storage, but it’s actually running as software on shared hardware.

Simple Example: Imagine the physical server as an apartment building 🏢 and each virtual machine as a separate apartment inside that building. Each tenant (VM) has its own furniture (OS and apps) but shares the same building (hardware).

What is Virtualization?

Virtualization is a technology that allows you to run multiple virtual machines (VMs) on a single physical machine. Each VM acts like a real computer with its own OS, CPU, RAM, and storage, but all share the physical server's hardware.

Real-world Example of Virtualization

Imagine one big server in your office. Using virtualization, you divide it into multiple small computers (VMs): one for email, one for web hosting, one for databases, and one for backup. Each VM does a separate job on the same hardware.

Why Do We Use Virtualization? - Cost Saving

You don't need to buy separate physical machines for each service. You save money by running multiple services on one server.

Why Do We Use Virtualization? - Better Resource Utilization

You use CPU, RAM, and storage more efficiently. Resources are not wasted like in underutilized physical machines.

Why Do We Use Virtualization? - Easier Management

You can create, delete, or move VMs easily without touching the physical hardware.

Why Do We Use Virtualization? - High Availability & Backup

VMs are easier to back up, clone, and restore quickly compared to physical systems.

Key Component: Hypervisor

The hypervisor is software that creates and manages VMs. It runs on top of the physical hardware.

Key Component: Virtual Machine (VM)

A virtual machine is a software-based computer that runs on the hypervisor and behaves like a real computer.

Type 1 Hypervisor (Bare Metal)

Installed directly on the physical server. Examples: VMware ESXi, Microsoft Hyper-V. Offers better performance and is used in data centers.

Type 2 Hypervisor (Hosted)

Installed like an application on top of a host OS (like Windows/Linux). Examples: Oracle VirtualBox, VMware Workstation. Used mostly for testing or learning.

What is a Snapshot?

A snapshot is a point-in-time copy of a system, virtual machine (VM), or storage volume. It captures the exact state of data, including settings, files, memory, and configuration, without moving data to another location.

Real-world Example of a Snapshot

Imagine you're editing a Word document. Before making big changes, you click "Save As" to create a copy. If something goes wrong, you go back to that saved version. A snapshot works similarly for systems or storage.

Snapshot Use Case - Virtual Machines

Take a snapshot before installing software on a VM. If the installation fails, you can revert to the snapshot instantly.

Snapshot Use Case - Storage Systems

Storage arrays take snapshots of disks to allow quick restoration of deleted or changed files.

Snapshot Use Case - Databases

Database snapshots capture the current state so you can roll back quickly if needed.

Difference Between Snapshot and Backup - Snapshot

A snapshot is a quick, instant copy of system state that stays on the same system or storage.

Difference Between Snapshot and Backup - Backup

A backup is a complete copy of data, moved to another location like external storage or cloud, suitable for long-term recovery.

Type of Snapshot - VM Snapshot

Captures the state of a Virtual Machine including OS, RAM, Disk, and settings.

Type of Snapshot - Storage Snapshot

Captures the state of a storage volume or disk at a specific point in time.

Type of Snapshot - Application Snapshot

Captures the state of specific applications like databases to restore them if needed.

Snapshot in Backup Systems

Tools like VSS (Volume Shadow Copy Service) use snapshots to make consistent backups while the system is running. Platforms like Datto, VMware, Hyper-V, and cloud services use snapshots to protect data and VMs.

What Are Shadow Copies?

Shadow Copies are snapshots of files or folders at a specific point in time. They allow restoration of previous versions without needing a full backup.

Real-World Example of Shadow Copies

You work on a file Monday, and a shadow copy is created Tuesday. On Wednesday, you accidentally delete it. You can restore the deleted file using Tuesday’s shadow copy.

Where Are Shadow Copies Used?

Used in Windows Servers and Professional Editions (via Previous Versions). Helps restore files quickly without full backup or support team.

What is VSS (Volume Shadow Copy Service)?

VSS is a Windows service that creates and manages shadow copies of files or drives even while the system is running. It enables consistent backups.

Real-World Example of VSS

A running database server can't be backed up directly due to file changes. With VSS, changes are paused briefly, a snapshot is taken, and backup proceeds with no corruption.

VSS Component - Requester

The component that initiates the backup process. Example: Backup software like Acronis or Datto.

VSS Component - Writer

The component that freezes apps to ensure safe backup. Example: SQL Writer, Exchange Writer, System Writer.

VSS Component - Provider

The component that takes the actual snapshot (shadow copy) of the volume. Example: Microsoft VSS Provider or third-party providers.

What Happens During VSS Operation

1. Backup software (requester) starts backup. 2. Writers freeze the system data. 3. Provider takes snapshot. 4. Backup completes and system resumes.

Why is VSS Important?

VSS allows backups while systems are live, ensures data consistency, and works with both agent-based and agentless backup tools.

VSS Troubleshooting Command

Run `vssadmin list writers` in CMD to check status. If no errors → all good. Errors/timeouts → VSS service may need restart.

What is Hyper-V?

Hyper-V is a Type 1 Hypervisor developed by Microsoft. It creates and manages Virtual Machines (VMs) on a physical server, allowing multiple OSes like Windows and Linux to run on the same hardware.

Real-World Example of Hyper-V

One physical server runs multiple VMs: Web Server, Mail Server, File Server — all isolated but using the same hardware through Hyper-V.

Hyper-V Feature - Virtual Machines (VMs)

Software computers created and managed using Hyper-V.

Hyper-V Feature - Virtual Switches

Virtual network connections allowing VMs to communicate internally and with the outside world.

Hyper-V Feature - Snapshots (Checkpoints)

Save the current state of a VM to roll back later if needed.

Hyper-V Feature - Resource Allocation

Allows assignment of CPU, RAM, and storage to each VM as required.

Hyper-V Use Case - Data Center Virtualization

Used to consolidate multiple servers into VMs on fewer machines.

Hyper-V Use Case - Test Environments

Allows quick creation and deletion of test VMs without extra hardware.

Hyper-V Use Case - Disaster Recovery Labs

Helps simulate failure and recovery in isolated virtual environments.

Hyper-V Use Case - Training Labs

Used in CCNA, CCNP, and IT training setups to create hands-on virtual labs.

What is ESXi?

VMware ESXi is a Type 1 Hypervisor created by VMware. It runs directly on physical server hardware and is part of VMware vSphere for enterprise virtualization.

Real-World Example of ESXi

You install ESXi on a bare-metal server and run multiple VMs like Database, Backup, and Application Servers independently on shared hardware.

ESXi Feature - ESXi Host

The physical server running the ESXi software layer.

ESXi Feature - VMs (Guest OS)

Virtual computers created and operated within the ESXi host.

ESXi Feature - vSphere Client

A management interface to control and configure ESXi hosts and their VMs.

ESXi Feature - Datastore

Storage location where all VM files (like VMDK and config files) are stored.

Hyper-V vs ESXi - Vendor

Hyper-V is from Microsoft; ESXi is from VMware.

Hyper-V vs ESXi - Type

Both Hyper-V and ESXi are Type 1 Hypervisors.

Hyper-V vs ESXi - Installation

Hyper-V is installed on Windows Server; ESXi is installed directly on server hardware (bare-metal).

Hyper-V vs ESXi - Management Tool

Hyper-V uses Hyper-V Manager or Windows Admin Center; ESXi uses vSphere Client or vCenter.

Hyper-V vs ESXi - Common Use

Hyper-V is common in SMBs and Windows environments; ESXi is widely used in large enterprise data centers.

What are Storage Arrays?

Storage arrays are special setups that hold lots of data in an organized way using many hard drives or SSDs.

What do you mean by Arrays?

Arrays are a group of storage devices like hard drives working together to store data safely and quickly by spreading data across all drives.

How do Storage Arrays work?

They combine multiple drives into one unit so that data is split up and copied across drives, providing protection if one drive fails.

Why are Storage Arrays useful?

They make data access faster, protect against data loss, and save space by managing storage more efficiently.

Real-world Example of Storage Arrays - Bookshelf

Think of a storage array like a library with many bookshelves (drives). Books (data) are spread out and copied so you can find or recover them easily if a shelf breaks.

Real-world Example of Storage Arrays - Team of Chefs

Imagine a kitchen where many chefs (drives) work together to cook (store) meals (data) faster and keep extra dishes in case one chef makes a mistake.