Throughout this course, we've constantly
mentioned how valuable it is to have a backup of your data.
This can not only allow you to go back in time
and retrieve a previous version of a file,
but this is something that can also
help you recover if you happen to have some type of disaster.
There are obviously a number of considerations
when planning a backup system.
You have to think about the total amount of data
you're going to be backing up and the type of backup
you're going to perform.
You also have to think about where you're
going to store all of this backup data
and on what type of media, and where
you plan on keeping all of these backups.
You also have to think about the software you're
using to manage the backups because that's also
the software you'll use to restore those backups.
You also have to think about the type of backup
that's taking place and on what day of the week
you'll be performing this backup.
A full backup is when you make a copy of everything that's
on a particular file system.
This would include operating system files, user documents,
and anything else that's installed on that system.
Because you're making a copy of everything
that's on that device.
This is usually the backup type that takes the longest.
Transferring terabytes of data from every system that's
on your network may not be practical to do
every day of the week.
And of course, you have to think about where you're
going to store all of this information
once you've created the backup.
To make this process a bit easier,
you may want to use a different type of backup
such as a differential backup.
With a differential backup, you first perform a full backup.
Every subsequent backup will only
contain data that's been changed since that last full backup.
That's the different part of the differential.
So if you perform this differential backup every day,
you'll notice that each day, the differential backup
gets larger, and larger, and larger as more information
has changed since the last full backup.
To restore this data, you need two pieces of information.
You need the last full backup and you need
the last differential backup.
Let's implement a differential backup on my network.
We're going to first start on early Monday
morning and create a full backup of all of the data
that's on a system.
We'll then perform a differential backup on Tuesday
morning, and this would obviously only
be the data that has changed since the last full backup.
We'll then perform another differential backup
on Wednesday.
This Wednesday backup is a differential backup
that only contains data that has changed
since the last full backup on Monday.
And then Thursday, we perform the same differential.
And again, this is only the data that
has changed since the last full backup.
Now let's say that the system has suddenly crashed
and we need to restore all of this data.
We'll grab the last full backup, that's
the one that was taken Monday, and the last differential
backup, in this example, it's the one from Thursday.
Put.
Those together and we've now recovered all of the data
on our system
An incremental backup starts exactly the same
as a differential backup where we take a full backup
before we do anything the next backup will
be an incremental backup that contains
changes that have occurred since the last full backup.
On this first day, this is very similar to the differential
backup that we just looked at.
However, things change a bit on the next backup day
where we're only going to back up
things that have changed since the last full backup
and since the last incremental backup.
This means this backup could be very small
if nothing has changed since the last incremental backup.
Each day of the incremental backup,
we are copying anything that has changed
since the last full backup and the last incremental backup.
The restoration process for this is
very different than the differential
because you not only need the last full backup,
you need each incremental backup that
has occurred since that last full backup was made.
So if we implemented an incremental backup,
we would of course take our full backup on Monday morning.
On Tuesday morning, we would only
copy the information that has changed
since that last full backup.
On Wednesday, we would only copy information
that has changed since Tuesday.
On Thursday, we would only copy information that
has changed since Wednesday.
And if we do need to recover the entire system at that point,
we would need to get all of these data sets together.
So we would need the full backup,
Tuesday's incremental backup, Wednesday's incremental backup,
and Thursday's incremental backup
to put them all together to create the full restore.
Earlier in this video, we talked about a full backup
and how it's very time consuming to copy all of the data
to create that full backup.
But what if there was a way to create
full backup without actually copying all of the data
from that system.
We can do that through something called a synthetic backup.
With a synthetic backup, we are creating that first backup
and then we have incremental backups that occur after that.
Then when we would like to create
a new synthetic full backup, we'll
simply take all of those data sets we had previously
and combine them all together into what ultimately becomes
the synthetic full backup.
This is obviously much faster than performing a full backup
because we already have all of these data sets backed up.
We just need to combine them all together
to create that synthetic full backup.
So let's say on our network we would
like to have a full backup on Monday
and a full backup on Friday.
So Monday morning, we will perform a full backup
and store that information in one data set.
We will then have incremental backups
that occur on Tuesday, Wednesday, and Thursday.
On Friday, instead of performing another full backup
by copying all of the data off of that system,
we'll simply combine all of these data
sets together offline to create the synthetic full backup.
From this point forward, we can continue
with our incremental backups because we now have effectively
created a full backup.
To summarize this, we have full backups,
which will copy all data selected on that system.
This obviously takes quite a bit of time
because we're copying all of that data
but it's very quick to restore because you only
need the single backup set created from the full backup.
With a differential backup, we're
backing up all data modified since the last full backup
each day.
This means we'll have a moderate backup time
as those backups become larger and larger each day,
and a moderate restore time because we only
need the last full backup and the last differential backup.
The incremental backup will backup all new files
and anything that's modified since the last incremental
backup.
This backup time is very low because we're only
copying things that have incrementally changed.
But it does have a high restore time
because you not only need the full backup,
but every incremental backup that has occurred
since the last full backup.
And with a synthetic full backup,
you have a copy of all of the data that's on that system.
It is a low backup time because we're
using an incremental backup every day.
And it's also a low restore time because there's
a single backup set which is our synthetic full backup.
Of course, backing up the data is only part of the job.
We also have to make sure that all of that data
can be restored.
So you may want to try simulating a disaster.
Take a completely clean system and try restoring your data
from your backups.
Then once the restoration is complete,
you can check the data to confirm
the operating system and all of your user data is intact.
This restoration should be scheduled on an ongoing basis
so that you can audit the backup process and confirm at any time
that you'll be able to restore all of your users' data.
One way to store data is to have all of your backups
occur on site.
This means you won't need any type of internet
or wider network link.
The data that you're backing up is immediately available to you
and you can use it to restore right
after you've made the backup.
And generally speaking, it's less expensive than having
an offsite backup system.
For an offsite backup, we obviously
need some type of network connection.
So this might be a wide area network or an internet link.
We also have to make sure that we
have a way to retrieve that data if we need access to it.
So if a disaster occurs, do we still have access
to our offsite backup.
But since this data is stored offsite,
you could effectively restore it to any system
regardless of where you happen to be.
In practical terms, many companies combine these.
So that you have some data that's
stored site and some data that's stored offsite.
This gives you multiple copies of the data
and gives you some options when it comes time
to restore that data.
One strategy for backups is to use the Grandfather, Father,
Son rule, or GFS.
This is three separate backup rotations
that occur at different times of the month.
You have a monthly backup, a weekly backup,
and a daily backup.
So you might have a full monthly backup that
occurs on the last day of the month
and you would consider that to be your grandfather backup.
At the end of the year, you would have
12 separate monthly backups.
You would also have backups that would occur once a week,
and each of those backups would be referred to
as the father backup.
And of course, you would take backups every day,
whether that's an incremental backup or a differential
backup.
And you can refer to those backups as the son backup.
So here's a common grandfather, father, son schedule
that you might set up.
You might have the grandfather or monthly backups
occur on the last day of the month.
You can see there's one on this 31st
and another one on the next 31st of the month.
You would then have weekly or father backups.
In this calendar you can see they all
take place on a Monday.
And then we would have daily or son
backups occur every workday.
The details of when you would perform these backups
will depend on how you want to implement them
in your organization.
As long as you have monthly grandfather backups,
weekly father backups, and daily son backups, then
you have everything you need for a GFS backup strategy.
Another popular strategy for backups is the 3, 2, 1 backup.
This is something you can use for your business.
It's also something you can implement at home.
The 3 in the 3, 2, 1 strategy means
that you will have three copies of data that
are always available to you.
There would be obviously the primary copy
that you would use on your system and then two
other backups that would be available.
The 2 is referring to the type of media that you would use
and you would need at least two different types of media.
So you might have a local drive, a tape backup, or a network
attached storage device.
Any two of those would satisfy the strategy
for a 3, 2, 1 backup rule.
And lastly, the 1 in the 3, 2, one
is that one copy of this data should be kept off site.
If something did happen to your business or to your home,
you would still have a copy of that data stored
somewhere safe.