User manual

Appendix G: Glossary

268 Cobalt Qube 3 User Manual

Redundant Array of Independent Disks (RAID)

A redundant array of independent disks is a way of storing the same data in

different places (thus, redundantly) on multiple hard disks. A RAID appears

to the operating system to be a single logical hard disk.

There are a variety of different types and implementations of RAID, each

with its own advantages and disadvantages. RAID Level 1 (RAID-1), also

known as disk mirroring, consists of at least two drives that duplicate the

storage of data.

Although RAID can protect against disk failure, it does not protect against

operator and administrator (human) error, or against loss due to

programming bugs.

RAID can be implemented in hardware or in software. Hardware RAID is

always a “disk controller”, that is, a device to which one can cable up the

disk drives. Software RAID is a set of kernel modules, together with

management utilities that implement RAID purely in software, and require

no extraordinary hardware.

Root name server

On the Internet, the root name server system is the manner in which an

authoritative master list of all top-level domain names (such as .com, .net,

.org and individual country codes) is maintained and made available.

SCSI

See Small Computer System Interface (SCSI).

Secure Sockets Layer (SSL)

Secure Sockets Layer is a program layer created by Netscape

Communications for managing the security of message transmissions in a

network. Netscape’s idea was that the programming for keeping your

messages conﬁdential ought to be contained in a program layer between

higher-level protocols (such as HTTP or IMAP) and the TCP/IP layers of the

Internet. The “sockets” part of the term refers to the sockets method of

passing data between a client and a server program in a network or between

program layers in the same computer.

SSL allows an SSL-enabled server to authenticate itself to an SSL-enabled

client, allows the client to authenticate itself to the server, and allows both

machines to establish an encrypted connection.