Problem #2 - RAID or NO RAID (or RAID 0 = also known as "Zero RAID!)

Let's assume your NAS has more than one drive in it. You might have been told or seen advertising on your NAS saying that it supports "RAID". But what does this mean?

RAID stands for "Redundant Array of Inexpensive Disks" - it's a general term used for the group of technologies and concepts behind using more than one drive in a team. RAID comes in many shapes and sizes. Some NAS drives - for example most NetGear ReadyNAS units have some specific and special types of RAID software that don't fit into the standard definitions. Those definitions (for the most common types, are):

RAID 0
This isn't "redundant" at all - but it is an array of disks. The clue though is in the number. "Zero RAID" - pretty much sums it up. It's a quick way to get the capacity of 2 drives put together as if it is one big drive, and a good number of NAS drives and/or people configuring them do this. The downside is that this means 50% of every file is on each drive - so if one drive fails, every file is effectively torn in half - making it useless. This is why RAID-0 is not a good plan - yet most NAS drives use this by default (we've even seen some desktop computers come with 2 drives like this - madness indeed).

RAID 1
This is the most common type of *actual* RAID we see in NAS drives - but sadly we don't see it too often. RAID-1 is effectively 2 drives with identical mirror copies - everything on one drive is on the other. This is good if a drive fails - losing one drive means everything carries on while you replace the faulty drive. It can also give you better performance in some situations - although most NAS drives are very slow so you won't benefit. The downsides are that you're wasting 50% of the space you have in theory because you're just storing it all twice.

The real danger here though is that too many people believe having RAID-1 means you have a backup of your data. They're wrong. You have precisely no backup - you just have 2 copies. And this means if you delete a file - it's deleted on both copies. If a file gets corrupted, it's corrupted on both copies - RAID-1 is effectively in "real time" - so errors are copied too. If the NAS RAID system has an issue it will corrupt both copies - this thus is a terrible false belief and leads many people to lose data. Don't do it.

	Criado por Jessica Gray mais de 8 anos atrás

Slides sobre What is Network Storage, criado por Jessica Gray em 25-05-2016.