Daniel Lemire's blog

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Solid-state drives: when external memory becomes as fast as internal memory

Steve Jobs just introduced the MacBook Air. The MacBook Air is thin and light, but what matters to me is that it uses a solid-state drive:

Using technology similar to that in the iPod nano and other Flash-based products, MacBook Air introduces a solid-state drive. This drive has no moving parts and can access data more quickly than standard hard drives, so you’ll enjoy a boost in performance when starting up your computer and opening files and applications. In addition, solid-state drives offer greater durability and improved resistance to data loss in the event of an accidental drop.

This follows recent announcements by storage vendors such as IBM and EMC who have started offering solid-state drives for enterprise needs. Solid-state drives are compelling:

  • Solid-state drives have access speeds about 250 times faster.
  • Solid-state drives use less power (over 30% less).
  • Solid-state drives are silent.
  • Solid-state drives are typically much smaller.
  • Solid-state drives are between 15 to 20 times more expensive, but prices are coming down.

I estimate that typical RAM is now only 10 or 20 times faster to access than a solid-state drive. These new drives lower the gap between internal and external memory. So, external memory becomes internal memory? Maybe not. For example, solid-state drives tend to have poor random write performance. You better write the data sequentially.

Disclaimer. I wish I was an expert on solid-state drives, but I am not. Please correct me if I am wrong.