Knowledge Base: Hardware

1. What kinds of network cards are being used?

2. What kind of hard drives are used in the servers?

3. What is SCSI?

4. What is the difference between SCSI and EIDE?

5. What is EIDE?

6. What is RAID5?

7. What is RAID1?

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1. What kinds of network cards are being used? - Top

Every server has dual 10/100 3Com NIC ports.

- Updated: January 26, 2006

2. What kind of hard drives are used in the servers? - Top

Every server consists of hot swappable Seagate SCSI Ultra-3 (Ultra160/m) 10,000 RPM (Revolutions per Minute) hard drives.

- Updated: January 26, 2006

3. What is SCSI? - Top

SCSI (pronounced SKUH-zee), the Small Computer System Interface, is a set of evolving ANSI standard electronic interfaces that allow personal computers to communicate with peripheral hardware such as disk drives, tape drives, CD-ROM drives, printers, and scanners faster and more flexibly than previous interfaces. Developed at Apple Computer and still used in the Macintosh, the present set of SCSIs is parallel interfaces.

The latest SCSI standard is Ultra-3 (sometimes spelled "Ultra3") which increases the maximum burst rate from 80 Mbps to 160 Mbps by being able to operate at the full clock rate rather than the half-clock rate of Ultra-2. The standard is also sometimes referred to as Ultra160/m. New disk drives supporting Ultra160/m will offer much faster data transfer rates. Ultra160/m also includes cyclical redundancy checking (CRC) for ensuring the integrity of transferred data and domain validation for testing the SCSI network.

In addition to faster data rates, SCSI is more flexible than earlier parallel data transfer interfaces. The latest SCSI standard, Ultra-2 SCSI for a 16-bit bus can transfer data at up to 80 megabytes per second (Mbps). SCSI allows up to 7 or 15 devices (depending on the bus width) to be connected to a single SCSI port in daisy-chain fashion. This allows one circuit board or card to accommodate all the peripherals, rather than having a separate card for each device, making it an ideal interface for use with portable and notebook computers. A single host adapter, in the form of a PC Card, can serve as a SCSI interface for a "laptop," freeing up the parallel and serial ports for use with an external modem and printer while allowing other devices to be used in addition.

- Updated: January 26, 2006

4. What is the difference between SCSI and EIDE? - Top

The primary difference is that SCSI (Small Computer System Interface) has a processor built into the drive which allows for faster read / writes. The EIDE (Enhanced IDE) drives rely on the CPU. SCSI is a good option if you are planning to run a database. EIDE is suitable for standard web serving.

- Updated: January 26, 2006

5. What is EIDE? - Top

Enhanced Integrated Drive Electronics.
Enhanced (sometimes "Expanded") IDE is a standard electronic interface between your computer and its mass storage drives. EIDE's enhancements to Integrated Drive Electronics make it possible to address a hard disk larger than 528 Mbytes. EIDE also provides faster access to the hard drive, support for Direct Memory Access, and support for additional drives, including CD-ROM and tape devices through the AT Attachment Packet Interface.

- Updated: January 26, 2006

6. What is RAID5? - Top

RAID Level 5 distributes the parity among the drives. This can speed small writes in multiprocessing systems, since the parity disk does not become a bottleneck. Because parity data must be skipped on each drive during reads, however, the performance for reads tends to be considerably lower. RAID Level 5 is n-1 meaning you lose the disk space of one drive in order to stripe data across the drives. A minimum of three drives is required for RAID5.

- Updated: January 26, 2006

7. What is RAID1? - Top

RAID Level 1 means that one drive mirrors the other. In the event that one of your drives fails, the other will immediately continue to serve data. An additional feature with RAID is that, if one drive is overtaxed, the overflow requests will be handled by the second drive. RAID1 requires two drives, but you will lose the disk space of one of the drives.

- Updated: January 26, 2006