The Career Value of a College Education
My present career is in Information Technology for a regional company. I work as a Senior Network Analyst in the Information Services Department, and provide support for all devices on the computer network. I work on a team of seven members with responsibility for over 400 file servers, 40 routers, and 120 switches at more than 60 locations. Our company runs a mixture of network operating systems including Netware 6, Windows 2000 server, AIX, and various flavors of Linux.
I provide second level support for file servers, network operating system, user administration, data backup, clustering, directory services, file permissions, and virtual tape libraries. I determine hardware standards, negotiate support contracts, and renew maintenance agreements for our network equipment. I wear many hats in the company, and it certainly keeps things very interesting and fast paced.
My primary job is to provide support for our company's storage area network (SAN). The SAN infrastructure includes fibre channel switches and adapters, disk subsystems, storage appliances, and management devices. The SAN provides external storage to our corporate file servers. It is also used to maintain a mirror of critical data to a disaster recovery site. According to Webopedia, "data mirroring is the act of copying data from one location to a storage device in real time." (Anonymous, n.d.). ]
A director appliance is a high-powered file server that controls the disk resources connected to the SAN. The director runs the Linux operating system with a proprietary application to manage the disk subsystem. Clients must be defined through the director's administration interface in order to gain access to disk resources on the SAN.
Data mirroring is also accomplished by using a director appliance. According to Kai Lamb (2004), upon initial creation of a mirror:
The primary and mirrored disks are synchronized to match data on both sides. This process is driven by the (appliance) software and does not involve the application server. After the synchronization is complete, all write-requests from the associated application server are delivered simultaneously by the appliance to both sides of the mirror. It is important to realize that the dual-write process is controlled at the appliance, not at the application server. With this design, only a single I/O request needs to traverse the front-end of the storage network, thereby eliminating the extra storage traffic created by host-based mirroring as well as relieving the host CPU from having to process dual write commands.
Data mirroring is often employed for disaster recovery purposes. The SAN disks are placed in two different geographic locations that are linked together via the company network and a data mirror is established between the two sites. The secondary site provides the SAN disk resources in the event that a physical disaster occurs at the primary site.