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Storage Backups

Data backup is a foundational IT practice that protects against device failure, accidental deletion, and data loss by maintaining copies of critical data on separate storage. Understanding backup types—full, differential, and incremental—and their trade-offs is essential for building an effective recovery strategy.

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About this video

When devices fail or data is accidentally deleted, a backup provides the means to recover. A backup is a point-in-time copy of data stored on a separate medium—cloud storage, removable media, or another physical drive—so that if the original is lost or corrupted, a restore operation can return the data to the state it was in when the backup was taken. Because source data changes continuously, that fixed reference point is what makes recovery reliable and predictable. Deciding what to back up is one of the first and most consequential planning decisions. Backing up individual files requires minimal storage but rebuilding a full system around recovered files can be time-consuming. Restoring an entire machine image is faster for full system recovery but demands significantly more storage space and longer backup windows. The right scope depends on the recovery objectives and the criticality of the data involved. There are three core backup types, each with distinct behavior and trade-offs. A full backup copies all selected data every time it runs, making restores straightforward but requiring the most storage and time. A differential backup captures everything changed since the last full backup, so each differential grows larger over time but a restore only requires the full backup plus the most recent differential. An incremental backup captures only what has changed since the last backup of any kind, keeping individual backup jobs small and fast, but a restore may require chaining together the full backup and every subsequent incremental in sequence. Effective backup planning means analyzing what data exists, how frequently it changes, how quickly it must be recoverable, and how much storage is available. The restore process is just as important to plan as the backup itself, since the value of any backup strategy is ultimately measured by how reliably and quickly data can be recovered when needed. Establishing a backup plan before data loss occurs is not optional—failing to plan for backup is planning to lose data.

What you'll learn

What's covered

Data Backup Fundamentals

Aligned to

CompTIA Tech+
6.7 Explain business continuity concepts.
CompTIA A+ Core 2
4.3 Given a scenario, implement workstation backup and recovery methods.
CompTIA Server+
3.7 Given a scenario, implement backup and restore procedures.
3.6 Explain the importance of disaster recovery.

Key terms

Backup
A copy of data captured at a specific point in time and stored separately from the source system, used to restore information in the event of data loss, corruption, or a security incident such as ransomware.
Full Backup
A backup that copies all data on a selected system, volume, or dataset regardless of when it was last changed.
Differential Backup
A backup that copies all data changed since the last full backup, growing in size with each run until the next full backup.
Incremental Backup
A backup that copies only data changed since the last backup of any type, whether full or incremental, resulting in smaller and faster backups.
Restore
The process of retrieving and applying backed-up data to recover a system or dataset to a previous state.
Recovery Point Objective
RPO
The maximum acceptable amount of data loss measured in time, defining how far back data must be recoverable.

Topics

Data Backup Backup Types Full Backup Incremental Backup Differential Backup Data Recovery Storage Management

Transcript

We know now that our technology and our devices can fail, and that could be problematic, especially if we have some sensitive data on these different drives. Or perhaps the drive doesn't fail, but somebody deletes data that they shouldn't have deleted and we need to retrieve that. That's where backup comes into play.

Backup is a way that we can have a copy of the data that we have on these different devices, so if anything were to ever happen to it, we could do a restore and be back up and running. Backup is grabbing a copy of our data and hopefully storing that backup copy on some other device. Maybe it's in the cloud, maybe it's on some sort of removable media, maybe it's on another disk drive somewhere else. So, grabbing a copy of it.

One of the keys to backup is that it comes from a specific date and time that we do that backup. Data is constantly changing on the source, but the data that we backed up comes from a specific date and time that we can fall back on.

What to back up

One of the considerations we have is what do we back up. We could back up a whole machine and all the data and everything on it. Or maybe we just back up one of the disks or volumes on it. Or perhaps we're just backing up a folder or a file that's on that.

Depending on what we choose, they all have their pros and cons. For instance, obviously a file is much smaller and we don't have to have a big backup storage of it. However, if we need to replace the whole machine, it could be much more in depth trying to set up the machine to access that file again. However, if we restore the whole machine just to access a file, that could also take a lot of time to do. So depending on what we're trying to accomplish, we would back up different elements of our data.

Types of backup

There are different types of backups. If we were backing up, let's say, a volume: if we were to do a full backup, it would back up everything on that volume. However, we could choose a differential backup. A differential backup is going to back up everything from the last full backup. If we are going to do an incremental backup, it's going to back up everything from either the last full backup or the last incremental backup, whichever one was last.

You can look at it this way. Let's say we had a full backup done at the beginning of a day, and then changes happen throughout the day. A differential would take everything, so let's say we did one right here — it would do everything from the last full. Same thing if maybe we do another backup right here, it would do everything from the last full. If we did it right here, everything from the last full. Versus an incremental: if we did it in those same time frames, it would do everything since the last backup.

The advantages and disadvantages of each of these is how long each one of these backups takes, and how much a restore takes. A restore is when we're going to restore the data and all the changes. A full backup would have to be restored, plus whatever incremental or differential is needed, and what that process looks like is going to depend on the type of backups.

The biggest thing is to analyze what data you have and what you're trying to achieve, and make sure you plan accordingly. You want to make sure that you have backups done ahead of time, and don't get caught where you're losing data that you wanted to have because you failed to plan for a proper backup solution.

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