Which RAID System Do I Need?
Your Data is valuable, and by making the decision to invest in RAID technology, your are investing in the protection of your business records, your digital media and your personal memories. Our world is a digital world, and the vast expansion of digital media in our professional and personal lives means huge volumes of data - and it all needs to be backed up. In as many places as we can afford.
The message is simple: BACK UP YOUR DATA. OFTEN.
By combining a suitable RAID Solution with reliable Backup Software, the two biggest risks to your valuable data can be mitigated. If you are concerned about the cost of a simple RAID system, consider the cost of doing all that work over again.
Before you consider whether you need a RAID system or not, it would be wise to consider the following:
1 - The professional or personal value of your Data
2 - The amount of storage space you will need in the next 12-18 months (the time it would take for you to consider upgrading to newer, better technology)
3 - Your current computer hardware setup (desktop, laptop, available interface ports etc)
4 - Your future expansion plans
5 - Your budget
Do I Even Need a RAID System?
Most computer users realise the need to back up their data. It takes a long time to accumulate data, be it client files, business records, professional media and photographic files, your personal photo collection or iTunes library, but it can take only seconds to lose it all!
Again, the message is simple: BACK UP YOUR DATA. OFTEN.
If you honestly don't feel that a RAID system is necessary, then a simple Backup Drive is all you need, either External or Internal. This is the absolute minimum, and should be as mandatory to every computer user as a printer, or for that matter as a keyboard and mouse. Maybe you have everything already stored on your Mac's main hard drive, and all you feel you need is one backup of that data:
You have two options:
External Hard Drive: A simple external hard drive, connected to your computer via USB, Firewire or if a PCI, PCI-X, PCI-Express or ExpressCard is used, via the superfast eSATA Interface.
USB2.0 Firewire400 and USB2.0 Firewire800 and USB2.0 eSATA, Firewire and USB2.0
Internal Hard Drive: If you have a desktop computer with a spare hard drive bay, you can add another Hard Disk Drive to your Mac or PC, and back up directly to this drive. You will need one of the following:
IDE/ATA Hard Disk Drive SATA Hard Disk Drive
Of course, by adding either an external hard drive or another internal hard drive, you are able to create a Software RAID Array at any time via your Disk Utility (Mac) or your Disk Management (Windows).
OK, I Need a RAID System:
Determining which RAID configuration to use depends on what is your biggest need. If storage space is your most important requirement and you are less concerned about data loss, then RAID 0 will work best for you. If you are concerned about data lose and don't need large amounts of storage space, then RAID 1 is your best choice. If you need a storage capacity over 1TB and are concerned about potential data loss, then RAID 5 or RAID 1+0 is what you should be looking at. Deciding between those two will often come down to how many disks your server can hold and how much money you can spend.
(Need help understanding the different RAID levels? Click HERE)
RAID 0 (Striping):
RAID 0 is one of the base configurations and is called striping. It requires a minimum of 2 disks. What occurs in a RAID 0 config is that the separate disks appear as one giant disk with space equal to the sum of the drives. This logical disk that is created has stripes which run across the other and can be thought of as the cylinders of the array, rather than the individual cylinders of the drives. The advantage of RAID 0 is that you gain storage space. However, if one of the drives goes bad, all data is lost. There is no way of retrieving it.
RAID 1 (Mirroring):
RAID 1 is the second base configuration and is called mirroring. It also requires a minimum of 2 disks and can only be used with an even number of disks. While RAID 0 provides increased disk space, RAID 1 instead provides data integrity and protection. When drives are placed in a RAID 1 configuration, any data written to one is also written to the other one. Therefore if one of the mirrored drives goes bad, no data is lost as it is on the other drive. The bad drive can be replaced and the data copied to the new disk. Many RAID 1 hard drives have an "auto-rebuild" function which rebuilds the failed hard drive automatically once it has been replaced.
Examples of 2 Bay External Hard Drives Supporting RAID 0 & RAID 1:
Taurus RAID II: Supports RAID 0, RAID 1 and J.B.O.D.
LaCie 2BIG Dual eSATA 1TB: Supports RAID 0, RAID 1 and J.B.O.D.
SATA Xpress RAID: Supports RAID 0 and J.B.O.D.
Stardom SOHORAID SR3610 FW800/USB2.0: Supports RAID 0, RAID 1, J.B.O.D.
Stardom ST3620 FW800/USB2.0: Supports RAID 0, J.B.O.D.
RAID 5 (Data Striping with a Parity Disk):
RAID 5 is one the most commonly used RAID configurations. It requires a minimum of 3 disks. RAID 5 uses the striping aspect of RAID 0; however not all of a stripe is made available for data storage. A part of each stripe is reserved for parity. This parity is used to ensure the integrity of the array. The amount of space reserved is equal to one of the disks. Thus 3 disks in a RAID 5 configuration will only provide you with equivalent space of 2 disks in a RAID 0. However, giving up the space of one drive means that if one of the disks fails, your data is not lost, as it would be in a RAID 0. You can replace the bad drive and rebuild the array. However, the array can only have one bad disk at a time. If two drives fail at the same time, then the array and all data is lost. It is for the reasons of increased disks space and data integrity that RAID 5 is one of the most common RAID levels.
RAID 5 Plus Spare incorporates a spare hard disk into the physical enclosure, but this disk is not part of the RAID 5 array until one of the hard drives in the RAID 5 array fails. If this happens, then the RAID 5 array will automatically rebuild the lost data onto the hot spare drive, from the RAID 5 parity drive. This is particularly useful for applications where downtime due to possible drive failure is not wanted. This means that the total available storage capacity in the RAID 5+spare array is the total number of hard disks less 2.
Examples of RAID 5 Systems:
ACARD 905E eSATA RAID: Supports RAID 0, RAID 1, RAID 5 & RAID 5+spare
Proavio EB4CR FW800/USB2.0/eSATA: Supports RAID 0, RAID 5 & RAID 5+spare
Stardom SR5600 Firewire800/USB2.0/eSATA: Supports RAID 0, RAID 1 & RAID 1+0
Stardom SR5650 USB2.0/eSATA: Supports RAID 0, RAID 0+1, RAID 5 & RAID 5+spare
All of the above RAID solutions have Onboard RAID Controllers - ie. the hardware RAID array is controlled by the inbuilt software in each of these external hard drive enclosures.
For a detailed explanation of the large range of RAID solutions with no onboard RAID controllers, and where all the raid controlling is done by a PCI or PCI-Express RAID card installed on your Mac or PC, please contact the Team at Epowermac on
