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First, consider RAID volumes. We haven't discussed them in this chapter because 
while the technology can still be beneficial, it's not as popular as it once was. Don't 
get me wrong, there's still a place for RAID, but it's just not as popular as it used to 
be (especially with ZFS in the process of being approved by Canonical for production 
use). RAID allows you to join multiple disks in various configurations that can 
result in a lesser chance of losing data. For example, RAID level 1 ensures that 
two hard disks always have the same data. If one of the disks physically fails, then 
you haven't actually lost anything. When you replace a failed disk in RAID, it will 
rebuild the array with the new disk and then you'll again benefit from having some 
expandability. RAID 5 allows you to have multiple disks to benefit from more space, 
and RAID 6 is the same but it allows you to have two disks fail before you lose data, 
rather than just one. Generally, that's the difference between one level of RAID and 
another; how many disks are allowed to fail before it becomes a problem.
However, RAID suffers from some serious problems. The worst is that it's 
not
 a 
backup solution. It doesn't advertise itself to be that, but many administrators 
mistakenly assume that their data is safe when utilizing RAID. The truth is, the level 
of protection RAID offers you is minimal. If there's a lightning storm and a power 
surge gets past your surge protector and fries a hard disk, chances are the other one 
will fry too. Generally, the environmental factors that cause one hard disk to fail will 
likely cause other disks to fail too. Worse yet, if a criminal breaks into your server 
room, grabs your server, and runs away with it, then the crook got away with your 
server 
and
 all the disks in your RAID anyway, so there are various scenarios where it 
won't save you. RAID can definitely be good to have, but it's more of a convenience 
than anything else.
Backups that are actually good exist off of the server, somewhere else. The further 
away the backup is from the source server, the better. If you store your backups in 
a drawer outside of your server room, then that's certainly better than leaving an 
external backup disk connected all the time (which can also be susceptible to power 
surges just the same as an internal disk). But if a terrible storm takes out your entire 
building, then having the backup disk stored in the same physical location will work 
against you.
It may seem as though I'm being a bit overly dramatic here. But actually, I'm not. 
These situations can and do happen. Successful backups are resilient, and allow you 
to get your servers up and running quickly. Backups of your data are on a more 
important level than that, as some companies can go out of business if they lose their 
important files, which can include things like schematics that enable the company to 
be in business in the first place. As a system administrator, you'll need to develop a 
backup scheme that will account for as many scenarios as possible.

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Managing Storage Volumes