An SSD crash course: What you need to know

Chances are increasing that you'll use flash memory for primary storage, but nasty surprises are possible with naive adoption

Solid-state disks (SSDs) are hardly new, but their growing usage represents a significant shift in the primary storage landscape. SSDs have been increasing in capacity and decreasing in cost at an accelerating rate, so the chances that you're going to bump into them in the wild are climbing as a result. However, SSDs are not perfect. A solid understanding of their history and differentiating factors will help you debunk some of the hype and leverage them more effectively in your environment.

The idea of a solid-state disk has been around for a very long time. Essentially, an SSD is persistent storage media constructed using transistors rather than an electromechanical disk or tape. SSDs have been holding the firmware for our switches, routers, cell phones, calculators, and just about any other kind of nondisk persistent memory for easily 30 or more years.

What is different today is that we're well down the path of using these SSDs in our enterprise primary storage environments -- either augmenting traditional disks or replacing them completely. This type of application for SSD hasn't been possible until recently due to the tremendous difficulty involved in constructing very large SSD memory modules that are cheap, reliable, and fast and that have a long lifetime. We're still working to overcome some of these challenges, and being aware of them is key to implementing them successfully.

Volatile versus nonvolatile SSDs

The biggest distinction to make right off the bat when talking about SSDs is whether they are volatile DRAM-based devices (RAM storage) or nonvolatile NAND memory (flash storage) devices. They both often fall under the SSD moniker, so it's easy to get them confused.

DRAM-based devices essentially use the same type of memory that makes up the primary system memory of your server; they are both extremely fast and susceptible to total data loss if power is interrupted for some reason. To combat this, most DRAM-based SSD devices require a battery backup to power the memory and ensure data integrity until power is restored.

1 2 3 Page 1
Page 1 of 3