Death and RAID On South Beach

 

I was burning out at work, and studying for the CISSP exam started to take it’s toll.  I needed a vacation.  

So here I was on a 3-night vacation in a warm paradise, and I still couldn’t stop thinking about the CISSP exam.

I thought about how horrifically against nature it would be if humans had a RAID system.  If we had backups of ourselves that could be used to replace us when we die.  

Pretty heavy stuff for just relaxing on the beach.  

What is RAID first of all? 

RAID stands for Redundant Array of Independent Disks.  So what does THAT mean? 

It means you take a bunch of hard drives, and chain them together in different ways so one hard drive has copies of itself on other hard drives.  Simple right?  

Anyway, below is an explanation of the RAID levels.  This topic pertains to operations security and is one of the ways to keep things running in a production environment.

IMG_0051

South Beach, Miami

We will be using the above picture to show how data is handled by RAID.

RAID – What Is It and Why Do We Need It?

Data is contained in hard drives.  Sometimes these hard drives fail. Companies use RAID to make sure there are multiple drives available with identical data in case one fails.

Parity: A bit of data that holds information that can be used to restore data 

RAID – O

RAID 0 stripes the data across different disks.  Do not use this for anything important  !

RAID

See how the beach picture is spread out (striped) across two drives? That’s RAID 0.

Advantage: Fast disk reads (Cuz data is not being copied, just distributed)

Disadvantage: NO fault tolerance, 1 drive failure is complete failure

Minimum Disks: 2

Note: DO NOT USE in mission critical applications

 

RAID – 1

RAID 1 copies everything in one hard drive to another hard drive.  It mirrors the data.

RAID_1 (1)

See how the beach picture is duplicated on both drives? That’s RAID 1.

Advantage: 100% fault tolerance/redundancy

Disadvantage: HIGH disk reading overhead, inefficient

Minimum Disks: 2

Note: Can be used for payroll/accounting

RAID – 2

For the CISSP exam, just remember RAID 2 is no longer used. It’s not that great and inefficient.

RAID – 3

RAID 3 uses striping at the byte level with a single dedicated parity disk.

RAID_3

 

Advantage: HIGH read/write of data, single disk failure tolerable

Disadvantage: Not meant for software RAID, complex controller design

Minimum Disks: 3

Note: For video/audio editing, apps requiring high throughput

RAID – 4

RAID 4 uses striping at the block level with a single dedicated parity disk.

RAID_4

Advantage: High data read rate

Disadvantage: WORST write rate

Minimum Disks: 3

RAID – 5

Striping at the block level with distributed parity across disks.

RAID_5

Advantage: High read rate, medium write rate, low impact if disks fail

Disadvantage: Very complex setup of central controller

Minimum Disks: 3

Note: Most common RAID implementation today

RAID – 6

Striping at the block level with double the distributed parity.

RAID_6

Advantage: Additional fault tolerance, more so than RAID 5

Disadvantage: Complex setup

Minimum Disks: 4

Note: Excellent fault-tolerance

RAID 1 through 6 will most likely be the ones to show up on the CISSP exam.

 

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