Raid Solutions - Grolen Communications, Inc. - One Stop

GROLEN RAID SOLUTIONS

In today's business world, network servers store invaluable data for companies. Backing up your data on a regular basis may not be enough. That's where
RAID protection takes over. GroLen builds network servers with various levels
of RAID protection - depending on your needs. Should a hard drive fail, RAID
can provide real-time, uninterrupted data recovery. With a GroLen RAID
server, your chances of data loss are greatly diminished, in fact - almost
nonexistent.

What Is RAID?

RAID stands for Redundant Array of Inexpensive (or sometimes "Independent") Disks. RAID is a method of combining several hard drives into one logical unit. It can offer fault tolerance and higher throughput levels than a single hard drive or group of independent hard drives.

The Benefits of RAID

Provides real-time data recovery with uninterrupted access when a hard drive fails
Increases system uptime and network availability
Protects against data loss
Multiple drives working in parallel increase system performance

Levels of RAID

	RAID 0	RAID 1	RAID 0/1	RAID 5
Description	Data striping (no data protection)	Disk mirroring	RAID 0 and RAID 1 combined	Data striping with distributed parity
Minimum # of Drives	2	2	4	3
Benefit	Highest performance	Data protection through redundancy	Highest performance with data protection	Best balance of cost / performance / data protection

The Types Of RAID

	Description	Advantages
Software-based RAID	Included in NOSs such as NetWare and Windows NT®. All RAID functions are handled by the host CPU which can severely tax its ability to perform other computations.	Low price Only requires a standard controller.
Hardware-based RAID	Processor-intensive RAID operations are off-loaded from the host CPU to enhance performance.	Data protection and performance benefits of RAID More robust fault-tolerant features and increased performance versus software-based RAID.
External Hardware RAID Card	Connects to the server via a standard controller. RAID functions are performed on a microprocessor located in the external RAID storage subsystem.	OS independent Build super high-capacity storage systems for high-end servers.

Server Technology Comparison

	UDMA	SCSI	Fibre Channel
Best Suited For	Low-cost entry level server with limited expandability	Low to high-end server when scalability is desired	Server-to-Server campus networks
Advantages	Uses low-cost ATA drives	Performance: up to 160 MB/s Reliability Connectivity to the largest variety of peripherals Expandability	Performance: up to 100 MB/s Dual active loop data path capability Infinitely scalable

Glossary

Array Two or more hard disk drives grouped together to appear as a single device to the host computer.

Bootable Array Support The ability to make the system boot from a RAID array instead of from a standalone (single) disk.

Cache A temporary, fast storage area that holds data from a slower storage device for quick access. Cache storage is normally transparent to the accessing device.

Co-processor A processor that resides on an array that relieves the host CPU from executing processor-intensive operations such as RAID 5 parity calculations and secondary RAID 1 writes.

Duplexing Mirroring across two RAID cards.

Dynamic Array Expansion See "Online Capacity Expansion"

Fault Tolerance The ability of a system to continue to perform its functions even when one or more hard disk drives have failed.

Hot Spare A spare hard drive which will automatically be used to replace the failed member of a redundant disk array.

Hot Swap The ability to remove a failed member of a redundant disk array and replace it with a good drive without bringing down the server or interrupting transactions that involve other devices.

Microprocessor A processor on the RAID card which performs all RAID management functions (for example, the Intel i960). Microprocessors offer higher performance compared to co-processors.

Mirroring (RAID 1) Provides data protection by duplicating all data from a primary drive on a secondary drive.

NOS Network Operating System (i.e., NetWare, Windows NT server)

Online Capacity Expansion (O.C.E.) A process for adding storage capacity to an existing RAID array without having to take the server offline. Also known as Dynamic Array Expansion.

Parity A form of data protection used by RAID level 5 to recreate the data of a failed drive in a disk array.

RAID Levels Numbered 0 through 5, RAID levels refer to different array architectures that offer various advantages in terms of data availability, cost and performance. RAID levels 0, 1, 0/1, and 5 are the most popular.

RAID 0 See "Striping"

RAID 0/1 Combines RAID 0 (data striping) and RAID 1 (disk mirroring).

RAID 1 See "Mirroring"

RAID 5 Combines data striping (for enhanced performance) with distributed parity (for data protection) to provide a recovery path in case of failure.

RAID Management Software Software that makes installation, configuration, and management of RAID arrays easy. Often includes features such as pager notification and remote management.

SCSI Stands for Small Computer System Interface. SCSI is the technology that allows you to connect various devices to your PC. This connection is made using a SCSI card that fits inside your computer.

Striping (RAID 0) Spreads data evenly over multiple drives to enhance performance. Because there is no redundancy scheme, it does not provide data protection.

Corporate Solutions | Consumer Solutions | Internet Solutions | Home