There are two types of people on earth, those who have lost data and those who do not backup. So in this episode, I want to talk about backups. In today's highly automated cloud based world, backing up seems almost trivial. I don't know about you. But with my high end Android phone, I can pretty much break it in half, buy a new phone, and everything pretty much magically comes back to life. So backing up is important.
But from an enterprise level, in particular, when we're talking about IP security, there are certain issues you're going to see on the exam. And I want to delve into these a little bit. So let's go ahead and get started first by talking about backup methods. Here I have a little computer and I want to back this computer up. Now we could back this up to an external hard drive, we could back it up to a tape. We could even back it up to the cloud today.
But the problem is, is that when we do a backup, the only thing we could do is backup everything now if we do a backup of everything better known as a full backup, that's absolutely fancy. pastic and it's an important part of any backup methodology. However, and let's assume we back up every day at the end of the day, as we go from Monday, Tuesday, Wednesday, Thursday and Friday. That means every day we are spending X amount of time doing a full backup. And do we want to keep making full backups every day? The answer's no, it takes a long time.
It puts in a lot of overhead. So if we can avoid that, let's go ahead and avoid that. And we can, we can do this because all file systems have features built into them that give us clues as to when files have been changed. Here, for example, is a Linux system. And I'm typing a command called stat on a file called Cleverley file. And if we look at this file, we'll see that it has a modified date.
And we could use that information to be able to determine from our last backup has this been modified or not. In a Windows system here, I'm running Windows on top of NTFS. We have what's known as the archive attribute The archived attribute is turned on whenever a file is created or changed. So as we look at these three files here, you'll see the first two, you see that letter A, that shows that they've been changed, the third one at the bottom has not been changed. Now using that we can do some cool things. We have two different options here.
The first one is called a differential backup. A differential backup basically means to backup all changes from the last full backup. The alternative is an incremental backup. The incremental backup only backups changes from the last backup of any type. Let me show you how that works starting with a differential backup. So here we have Monday, Tuesday, Wednesday, Thursday, Friday, at the end of the day on Monday, we make a full backup.
Now on the end of the day on Tuesday, by reading this file information, we can only make a backup of the files that have changed on that one day. Now on the next day, we make better backups of all the files that have changed. Remember, differential means since the last full backup. So this backup is going to be all the changes on Tuesday and Wednesday. On the end of the day, on Thursday, we do another differential backup. And in this case, we have all the changes of Tuesday through Thursday.
And then on Friday, everything from Tuesday through Friday. The nice part about a differential backup is that you only need two backups to be able to restore. So let's say it's Friday, and we've lost everything. In that case, what we do is we grab our full backup from Monday. And we grab our backup on Thursday, which reflects everything that's happened since that last backup. And with these two backups, we can completely restore the system.
Differential backups are fantastic because if you're using a weekly backup format, as many, many people do, you're only going to have two backups that you worry about at any given moment. Your full backup and then Whatever differential backup is important for you for whatever you want to do your restore from. So differentials fantastic, you have a very small number of backup sets. However, backup sets get bigger and bigger and bigger over the course of your backup period. So there's an alternative to this. The alternative is incremental.
Let me show you how that works. So let's start off once again, by having our full backup on Monday. Now keep in mind, we're going to be doing an incremental backup. So in this case, what we're going to do is we're going to at the end of the day on Tuesday, make a backup of only that which has changed on Tuesday. Now, when Wednesday comes along, we'll make another backup, a separate backup of everything that changes on Wednesday, and the same with Thursday and Friday. Now, let's imagine that Friday comes along and we've had a corruption and we need to restore using an incremental backup.
I'm going to need my full backup, plus everything from Monday, plus everything from Tuesday, plus seven Anything Wednesday, plus everything from Thursday in order to create a complete backup. So generally when we're talking about backups, I don't care what your methodology is, I don't care what you're backing up to. But you're almost always going to be in a situation where you're using full backups combined with either incremental or differential depending on your needs. The answer is easy differential. There are less backup sets, but they get bigger, incremental, more backup sets, but smaller. All right.
Now there is one other type of backup that comes into play, and that is snapshots. Now we see snapshots, typically under virtual machines, and they are an absolute perfect way of making a copy of something that's happened in the past. The only downside to these types of things is that snapshots are traditionally not stored on separate media. There's nothing against doing that here at total seminars when we make important snapshots. We add them to our backup sets, and they're part of our overall backup process. Alright, so So you've got all of these backups.
So what are you going to do with them? So, first of all, you have to decide on your media. Number one, if you go old school here, you're talking about local backups. Now, these could be tapes. These could be external hard drives, and they could be a separate backup that's stored locally, local backups have one big benefit. They're nearby in case anything messes up.
So you can imagine the alternative, which is an off site backup is not nearly as convenient, however, has one big benefit. And that is, if you catch fire or explode or something terrible happens, you have a remote backup. What we'll see in a lot of situations is that we will keep local backups, but then we also have a second off site backup, just in case. Now if you really want to be cool, the fun way to do things is using cloud backup. Cloud backups work beautifully. However, they have one big downside and that is they take up a a tremendous amount of time to get the initial backups going.
So that first full backup that you're going to do can take quite a while. However, once that's made, what you'll see with most cloud backup providers, is they do pretty much a continuous, ongoing incremental backup. So once it's made, it can be a very, very powerful tool for keeping your data intact.