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 by 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 I.T.
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 can 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 can do is backup everything.
Now if we do a backup of everything better known as a full backup.
That's absolutely fantastic and it is an important part of any backup methodology however.
And let's assume we backup 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 is 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 cleverly 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 archive attribute is turned on when ever 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 is that 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 backup 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 backup of the
files that have changed on that one day.
Now on the next day we make 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 is 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 everything
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's easy differential.
There are less back ups 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 stamp shots 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.
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.
Nearby in case anything messes up.
So you can imagine the alternative which is an offsite backup is not nearly as convenient.
However that's 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
offsite 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 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.