Building Your Encoding Hardware - A Practical Guide to Video and Audio Compression - page 458

Storage is aggregated into one block rather than separate blocks on a per-user
basis.

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Bandwidth can be allocated and reserved.

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So you have several items of significant cost to add to your system in order to make a
SAN system work. The SAN storage systems are not intended for single-user or small
workgroup situations. They are justified if you have a group of people working on
Hollywood movie production or commercials with massive throughput and fast work-
stations.
Some projections of enterprise deployments suggest that SAN installations will be
twice as common as DAS installations by 2007. Right now the DAS approach outnumbers
SAN by 2 to 1.
The biggest disadvantage of SANs is that they are very expensive to install and out
of the reach of everyone apart from the high-end users. This may change, because Apple
has been driving down the cost of this kind of enterprise-level computing for several years
now and the xSAN product is another step in reducing the cost of ownership of the SAN.
Even so, the cost requires a solid business case to justify it.

29.9.5 High-End Solutions

If your requirements are at the top end of the performance spectrum, you might want to
look at products by companies such as Apple, Rorke Data, or Storage Tek. These and other
companies in the same market have storage architectures that are optimized for the stor-
age and delivery of video, which must have large capacity and very rapid access with low
latency. Unfortunately, this performance level costs a lot of money.

29.9.6 Storage-Capacity Planning

The memory capacity necessary when building systems is predicted to more than double
each year. When this growth is compounded, it is easy to reach astronomical sizes of disk
farms within just a few years. That presents some very interesting problems. For instance,
how do you back it all up?

Digitize some known reference or test content (squares and circles, perhaps)
to calibrate your sample rates to your working canvas. Get the geometry right.

Apple XSAN: http://www.apple.com/xsan/
Rorke Data: http://www.rorke.com/
Storage Tek: http://www.storagetek.com/