add arrow-down arrow-left arrow-right arrow-up authorcheckmark clipboard combo comment delete discord dots drag-handle dropdown-arrow errorfacebook history inbox instagram issuelink lock markup-bbcode markup-html markup-pcpp markup-cyclingbuilder markup-plain-text markup-reddit menu pin radio-button save search settings share star-empty star-full star-half switch successtag twitch twitter user warningwattage weight youtube

What the frickityfrack is a buffer cache?

NerdyTurd
  • 17 months ago

So I've been doing research on different SSDs and which one I should use as for my PC, the SSD will be the main storage, no HDD. I've found that more expensive SSDs have caches, and I was wondering what caches are, as I've been trying to find out what they are but the only things I've found on them make absolutely no sense to me.

For example, I've been comparing the SanDisk SSD Plus (https://uk.pcpartpicker.com/product/x28H99/sandisk-ssd-plus-480gb-25-solid-state-drive-sdssda-480g-g26) the Kingston A400 (https://uk.pcpartpicker.com/product/WGZ2FT/kingston-a400-480gb-25-solid-state-drive-sa400s37480g) and the Crucial MX500 (https://uk.pcpartpicker.com/product/ft8j4D/crucial-mx500-500gb-25-solid-state-drive-ct500mx500ssd1) and while comparing, found out the MX500 has a 512MB cache while the others do not. Is there a Crucial (HAH! Pun intended.) difference?

Thanks!

Comments

  • 17 months ago
  • 3 points

Hi NerdyTurd. I am in no way a computer guru, but from what i understand cache memory is a separate memory chip/section on the ssd where info is stored for quick/frequent access, as opposed to being stored on main disk memory where it would take a little longer. hope this helps. If i am wrong i'm sure someone would be able to explain correctly. Good luck with choosing which one you want.

Regards, 8bitbro

  • 17 months ago
  • 2 points

Thank you so much! :) That really helps me understand it more.

  • 17 months ago
  • 2 points

You're welcome. :)

  • 17 months ago
  • 2 points

I think this is an almost perfect explanation. You did good 8bitbro.

  • 17 months ago
  • 2 points

Well awesome. Thanks. :)

  • 17 months ago
  • 1 point

Your welcome.

  • 17 months ago
  • 3 points

8bitbro explained it well. However, there is one other consideration, which is that for most usages it doesn't really matter much. There are a lot of other overheads involved besides SSD transfer rate, so you might see a game load taking 1.2 seconds on one SSD and 1.4 on another, or boot times being 12 seconds instead of 15.

There are certainly usages where it matters, and some people are more sensitive than others. But I'm going to suggest that for most general purpose home and gaming builds, SSD's can be treated as commodity items to be bought on price. If it's a photo or video editing computer, or an income producing machine, that's different.

  • 17 months ago
  • 1 point

Thanks for the help! I'll just go with the cheapest SSD then. :)

  • 17 months ago
  • 1 point

Don’t do that

You end up with sub-HDD speeds and terrible lifespans

If you want a more budget SSD something like an MX500 is good

  • 17 months ago
  • 1 point

Oh, I didn't mean it literally. I'm very careful with picking parts and always do way too much research on them. I'm thinking about going with an A400 or Adata SU650.

I was going to go with an MX500 at first, but its about £10 more expensive. I'll figure it out :)

  • 17 months ago
  • 1 point

Remember that max speed will never actually happen in general usage due to overhead and other variables :)

  • 17 months ago
  • 1 point

Go watch Linus’ video on how he used a intel Optane cache for a steam drive

  • 17 months ago
  • 1 point

I'd be interested in a history of that sort of thing from any SSD currently sold by any reliable vendor, even the super-cheap stuff.

I should have qualified my statement with "any SSD from a reputable source", I guess. But I'd be hard pressed to find a sub-HDD speed from any SSD, unless you're buying it from some guy who made it in his basement.

  • 17 months ago
  • 1 point

Until recently, lack of DRAM on a SSD was a terribly bad sign that you were buying the cheapest of the cheap SSD. I'd certainly recommend something more like a MX500 (or any crucial SATA) as a "bottom price".

But since then I've seen reasonably good reviews of things like ADATA NVMe cards, which while certainly not competing with the top line NVMe cards, they competed on price with the Crucial SATA lines and seemed to equal or beat any SATA performance spec. I'd want to dig into as many benchmarks of anything without DRAM, but don't be too surprised if a reputable company has made a chip that is "pretty good for the price" out of it.

Just don't expect top performance without DRAM (or similar buffer memory).

  • 17 months ago
  • 1 point

There are different kinds of caches. There can be a DRAM cache which stores data in volatile memory; this helps read performance but not synchronous writes, since the drive can't safely acknowledge the write until it's been written to persistent flash (unless it's an enterprise drive that has capacitors, or the drive lies and returns before the data is saved). Some drives (I think the higher-end Samsungs) have a portion of the flash used as SLC; SLC is faster than MLC so this speeds up synchronous writes.

Also Intel's Optane drives are very fast but do not have a cache; they achieve this by using a much faster (and more expensive) technology for their main storage.

For enterprise workloads (e.g. databases), caching with power-loss protection is very important due to the performance it can provide on synchronous writes. For some desktop workloads the on-drive cache may not matter very much, since your OS has its own RAM buffer for reads and non-synchronous writes.

Sort

add arrow-down arrow-left arrow-right arrow-up authorcheckmark clipboard combo comment delete discord dots drag-handle dropdown-arrow errorfacebook history inbox instagram issuelink lock markup-bbcode markup-html markup-pcpp markup-cyclingbuilder markup-plain-text markup-reddit menu pin radio-button save search settings share star-empty star-full star-half switch successtag twitch twitter user warningwattage weight youtube