4 Keys To Storage Management: Page 2 of 3

Storage Management Capacity

Storage management capacity consists of providing sufficient data storage to authorized users at a reasonable cost. Storage capacity is often thought of as large quantities of disk farms accessible to servers or mainframes. In fact, data storage capacity includes main memory and magnetic disk storage for mainframe processors, midrange computers, workstations, servers, and desktop computers in all their various flavors. Data storage capacity also includes alternative storage devices such as optical disks, magnetic drums, open reel magnetic tape, magnetic tape cartridges and cassettes, digital audio tape, and digital linear tape. When it comes to maximizing the efficient use of data storage, most efforts are centered around large-capacity storage devices such as high-volume disk arrays. This is because the large capacities of these devices, when left unchecked, can result in poorly used or wasted space.

There are a number of methods to increase the utilization of large-capacity storage devices. One is to institute a robust capacity planning process across all of IT that will identify far in advance major disk space requirements. This enables planners to propose and budget the most cost-effective storage resources to meet forecast demand. Another more tactical initiative is to monitor disk space usage to proactively spot unplanned data growth, data fragmentation, increased use of extents, and data that has not been accessed for long periods of time. There are a number of tools on the market that can streamline much of this monitoring. The important element here is the process, rather than the tool, that needs to be enforced to heighten awareness about responsible disk space management.

The advent of the personal computer in the 1970s brought with it the refinement of portable disk storage beginning with the diskette or so-called floppy disk. Early versions were 8 inches wide, stored 80 kilobytes of data, and recorded only on one side. Refinements eventually reduced its size to 3.5 inches and increased its capacity to 1.44 megabytes. By 2001, both Sony Corporation and Phillips Electronics had refined and offered to consumers the universal serial bus (USB) flash drive. These devices were non-volatile (they retained data in absence of power), solid state, and used flash memory. More importantly, they consumed only 5 percent of the power of a small disk drive, were tiny in size, and were very portable. Users have come to know these devices by various names, including:

Storage Management Performance

There are a variety of considerations that come into play when configuring infrastructure storage for optimal performance. The following list shows some of the most common of these. We will start with performance considerations at the processor side and work our way out to the storage devices.

The first performance consideration is the size and type of main memory. Processors of all kinds -- from desktops up to mainframes -- have their performance impacted by the amount of main storage installed in them. The amount can vary from just a few megabytes for desktops to up to tens of gigabytes for mainframes. Computer chip configurations, particularly for servers, also vary from 128MB to 256MB to forthcoming 1GB memory chips. The density can influence the total amount of memory that can be installed in a server due to the limitation of physical memory slots.

In smaller shops, systems administrators responsible for server software may also configure and manage main storage. In larger shops, disk storage analysts likely interact with systems administrators to configure the entire storage environment, including main memory, for optimal performance. These two groups of analysts also normally confer about buffers, swap space, and channels. The number and size of buffers are calculated to maximize data-transfer rates between host processors and external disk units without wasting valuable storage and cycles within the processor. Similarly, swap space is sized to minimize processing time by providing the proper ratio of real memory space to disk space. A good rule of thumb for this ratio used to be to size the swap space to be equal to that of main memory, but today this will vary depending on applications and platforms.