RAID Storage
In photography, imaging or design, our data is one of our most precious assets.
The thought of losing a current job or hundreds of hours work or thousands of personal photos is enough to make anyone grab for a bucket!
RAID is an acronym for Redundant Array of Independent Disks. With RAID enabled on a storage system you can connect two or more drives in the system so that they act like one big fast drive or set them up so that one drive in the system is used to automatically and instantaneously duplicate (or mirror) your data for real-time backup. Now, the exact speed and reliability you'll achieve from RAID depends on the type of RAID you're using.
RAID systems come in many various sizes and types. The variable that change are :
- size (how many drives can be used)
- interface (ThunderBolt™, FireWire, USB, eSATA, Fibre Channel, SCSI, Ethernet, iSCSI, SAS and more)
- other redundancy (support for multiple power supplies and RAID controllers)
Below we talk a little about RAID storage systems mainly in relation to desktop style models that connect directly to your Mac or PC.
RAID is NOT backup!
It's important to understand that RAID is a measure of protecting against hardware failure.... it is not a backup! RAID does not protect against the following failures/issues :
- Accidental deletion of files
- File corruption
- Accidental breakage (that cup of coffee or dropping it off a desk)
- Catastropic damage (fire!)
- Theft (if they want to get in, they will)
In saying that RAID can be a great way to protect against that all too regular hard drive failure (except RAID 0 - read more below).
Advantages of RAID
There are three reasons you might want a RAID system of drives.
- You need tons of storage space and you need it to be fast. (RAID 0)
- You want to instantaneously and automatically create 2 copies your data on 2 different drives. (RAID 1)
- You want both. (RAID 5)
Which RAID mode should I use?
1. RAID 0 - Speed
RAID 0 is taking any number of disks and striping data across all of them. This will greatly increase speeds, as you're reading and writing from multiple disks at a time. An individual file can then use the speed and capacity of all the drives of the array. The downside to RAID 0 though is that it is NOT redundant, the loss of any individual disk will cause complete data loss.
Pros :
- Very Fast storage performance
- High capacities (combining capacity of multiple drives together)
Cons :
- No tolerance for drive failure (all data would be lost if one drive fails)
Good for/as :
- Situations where non-critical but high speed storage is required
- Backup devices using Time Machine
- High speed Video data storage
- PhotoShop scratch disks
2. RAID 1 - Data protection
RAID 1 is also known as "mirroring" and is generally used with a pair of hard drives. The point of RAID 1 is primarily for redundancy, as you can completely lose a drive, but still stay up and running off the additional drive. You can then rebuild the array to a new drive off of the other drive with little to no downtime. RAID 1 also gives you the additional benefit of increased read performance as data can be read off any of the drives in the array. The downsides are that you will have slightly higher write latency, since the data needs to be written to all the drives in the array, and you'll only have the available capacity of a single drive.
Pros :
- Will protect against a single drive failure
Cons :
- Capacity is limited by drive size
Good for :
- Storage of important information
- Your System/Application drive (to minimise downtime in the case of hard drive failure)
- Small Servers for data storage
3. RAID 5 - Data protection and speed
RAID 5 combines the concepts of RAID 0 and RAID 1.
RAID 5 requires the use of at least 3 drives and will take the idea of RAID 0, striping the data across multiple drives to increase performance, but also adds the aspect of redundancy by distributing parity information across the disks.
Pros :
- Will protect against 1 or 2 drive failures (depending on configuration)
- Fast storage performance
Cons :
- Some disks are not used for capacity (i.e. used for parity or hot spare in case of failure)
Good for :
- Storage of important information
- Small and Large Servers for data storage
- When large amounts of storage are required
- High speed Video data storage
