December 1998

Tips and Traps

Why? The more features you add to Netware, the more memory it needs to run properly. Some components, like Java, need massive amounts of memory. Java alone needs 48 megabytes to run. As you add additional features, tools and components, your hard drive requirements go up as well.

A new Novell installation may use just 200 megabytes of storage, but in the long term, you'll need as much as ten times that. For example, if your system crashes and you need to do a memory dump, you need free space on your hard drive equal to the amount of memory in your computer. To do a core dump of a server with 128 megabytes of memory, you need at least 128 megabytes of free hard drive space.

Sorting Through Your Storage

A network that has been in service for a long time accumulates all manner of storage devices, from simple desktop computer hard drives to advanced server-based RAID subsystems. One of the hardest tasks is to decide what kinds of files should be kept on which storage devices. The simplest method of storage management is simple migration of the oldest files to the slowest and least expensive storage media.

For many companies, the slowest and least expensive storage tends to be the oldest storage equipment. It may not be a good idea to migrate your oldest files to such a system. Just because files are old, doesn't mean they aren't still mission critical. Older storage systems are more likely to become obsolete and can either orphan your oldest files or require you to perform a costly or time-consuming copy operation to more modern storage.

For long-term off-line storage, select a system that is durable and that offers market longevity. DLT tape and CD-ROM are storage media that have exhibited both long term archival qualities and have a proven track record of staying power in the market. This will ensure that if you ever need to access storage media ten years down the line, you will be able to find the equipment needed to access it. Set aside funds in your storage budget to migrate long-term archives to more modern media. This will keep your oldest files available in case you need them.

As for your older storage equipment, you can use it to archive non-mission-critical files or migrate it to a department that has been underserved by IS.

Get Selective With RAID

RAID storage is fast and massive. How many RAID systems have you seen smaller than 100 gigabytes? RAID storage is also expensive, relatively speaking. In an effort to maximize the investment in RAID, many users are tempted to put as much information on the system as possible.

Don't! RAID storage should be confined to those files that will benefit users the most by being on a shared storage resource. That means RAID should be off-limits to files that will not be shared. Individual user files are best kept on local desktop storage. RAID storage should also be kept off-limits to archival storage, unless interest in the archived files has been revived for a project.

RAID storage should be used for shared resources like databases, accounting information, current marketing and publication files and mission-critical files that require the speed and extra reliability of a RAID system.

Cram Course
Storage Area Networks

One of the hottest storage technologies today is the storage area network. In a storage area network, each storage element is connected through a thin server to a special high-speed network set aside just for storage devices. Any storage subsystem can be connected to a storage area network: CD and MO jukeboxes, RAID systems, tape libraries, WORM libraries and COLD systems.

RAID systems require their own controller cards, as do CD and MO jukeboxes and tape libraries and arrays. Devices in a storage area network can be connected via SCSI but more often are connected via gigabit ethernet or fibre channel.

The storage area networks are more expensive to implement because each storage device needs its own independent controller, more expensive connectivity hardware and more software. The advantages include improved reliability, greater flexibility, lower operating costs and better scalability.

Reliability is improved because you are not dependent on a single server running all the storage drivers. If a server goes down, all the storage devices usually remain up and running. If a storage device goes down, other storage devices on the network are unaffected. Server clusters are better supported, so if one server goes down, you can migrate the network traffic to a backup server.

Flexibility is improved because adding storage is as simple as adding a network client. You don't have to reconfigure a server. They scale better because you can add as many additional storage devices as the network can support -- usually several hundred devices. All different types of servers can coexist.

While more expensive to implement, storage area networks can save you money in the long run because adding storage doesn't require a new server or complex server setup.

Finally, you can add any kind of server to a storage area network. Windows NT servers can be added for the sales and marketing departments, Unix servers can be used by accounting and manufacturing and Macintoshes can be added for the creative/multimedia department. All these different server can coexist and share the same storage resources.