Velocidad de rotación de 10000 rpm interno SAS 600 GB de capacidad de almacenamiento de las unidades de disco duro

How to Balance Hard Drive Speed Against Capacity

One question that always comes up when dealing with hard drives is whether its more important to go with a larger drive or a faster drive. In truth that question has no single answer, because it depends on the situation.

What is SAS?

Also known as Serial Attached SCSI, SAS is a storage interface thats designed for use in the enterprise. Where other hard drives aim primarily for storage and archiving, SAS hard drives hold working data sets. This means that theyre working all the time, with heads moving back and forth as they seek data. There are three areas where these hard drives tend to excel:

  • Reliability: SAS hard drives are for operating for over a million hours in the harsh conditions of a server room. Not only are their service lives longer, but theyre able to operate reliably at much higher temperatures.
  • Transfer Speed: The SAS interface operates at up to 6 Gbps, and these internal hard drives also feature spindle speeds of 10,000 RPM or greater so that you can transfer several GB of random data quickly.
  • Seek Time: This often underrated figure refers to the speed at which the head moves across the disk. Disk drives store data in a series of concentric circles, and the head has to be over the right track to read the data. A lower seek time means the head moves to the right position faster.

What Should You Look for in a Drive?

Choosing hard drives can be as much art as science. You have to balance how many GB you need to store against how fast you need to access them. Luckily, in many cases you can get the majority of the information you need to make a choice from two data points.

  • Capacity: Each drive can only hold so many GB of data. For SAS, which generally uses larger numbers of smaller drives than many consumer applications, something in the 600 GB range is often more than large enough.
  • Spindle Speed: The higher the speed, the faster the hard drive. A speed of 10,000 RPM or higher means data moves under the heads more rapidly, which both increases transfer rates and reduces latency.

What Can You Use SAS For?

SAS hard drives are very well suited for database servers that spend a lot of time providing access to random data. They are also useful for shared storage in conjunction with multiple co-located servers. The high reliability means that they can offer the uptime you need in mission-critical applications, without risking your data. Its less suited for consumer use due to the relatively low capacity and high power requirements.

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