What Are DRAM-less SSDs?

Mature Amateur

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  1. Surely the drive keeps the index on the nand regardless. DRAM is volatile, and the index needs to be cached every time you power it on. Reads don't 'wear' NAND. I can see how storing the cache in system RAM can add a little latency, but is it that super bad? It seems like these are just 'Lite' drives, designed to be cheaper by removing what they can, including the warranty. I think I'd use one of these over a spinning rust drive any day.

  2. The primary benefit use of dynamic ram in a storage drive is caching in and out of the storage whether it is magnetic, optical or solid state is irrelevant.

    SSD maps are always maintained in non-volatile ram. In an SSD with DRAM cache, that map is copied from nvram during startup, and used until an error is detected. Once errors are detected, if the drive does not update the map, performance will degrade

    If read/write speed of non-volatile ram is sufficiently fast to match the processor bus speed then caching isn't needed.

  3. Dram-less SSD is almost like using an eMMC (embedded MMC, which a lot of mobile devices do to cut costs.. tablets, netbooks, etc). It's just solid-state integrated storage.. but uses the systems external ram and resources to do all mapping, no wear-levelling, etc. Only difference is you can remove a dram-less ssd from a system. eMMC is often glued or soldered in place.. hence "embedded".

  4. Hello, Linus! I love this video so much, and I want to make sure everyone can understand and enjoy it. That's why I wanted to let you know that your captions are a little off.

    At about 0:41 the auto-captions say "ran" where they meant to say "ram".

    When you get a chance, could you fix that? That'll help the 360 million folks globally who rely on closed captions to understand videos. Thank you, and keep up the great work!

  5. I have a question, ddr4 ram is very expensive, but you can also use a usb stick as ram for 6 bucks. So is a usb stick much slower? I dont get it, you can save a lot of money with a usb stick

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