3 ms·

So, unlike doty said below, we shouldn't treat SSDs like a faster form of spinning rust? Where do we find real advice about how to best utilize SSD?

baruch 12y ago
There is unfortunately no good place to do that. I work in an enterprise setting and get to talk to the ssd vendors and fish for details on how to best use their ssds and I still find it hard to get full information. Sometimes I wonder if there can even be a single compendium of knowledge about ssds. There are just so many moving parts in there that I doubt the ssd vendors themselves know what is really happening. Many times there are strange behaviors that we hit and then the vendors get to debug their ssds and explain new things about what just happened. One effect that I can attest to is that I know quite a bit about the ssd inner-workings (or at least how it shows to the outside world, never saw an ssd firmware source line) but it would be very hard for me to sit down and write something about all aspects. I can however answer questions when needed.
- joshuacc 12y ago
  > There are just so many moving parts I found this amusing in the context of SSDs versus spinning rust. :-D
  - baruch 12y ago
    Indeed :-) If you really want to be pedantic, there are electrons moving in there so it is solid state but it has moving parts :-)
danielvinson 12y ago
You can't really optimize for SSDs in general. You CAN optimize for a specific brand/model/controller on a certain chipset. If an optimization in general is possible, you can be sure that the SSD manufacturer already is utilizing it in firmware on higher-end drives.
baruch 12y ago
Unless you are optimizing for a specific SSD with known quantities there is no real way to do that. The high-level optimizations are important: * Choose a good SSD * Read and Write in "page" multiples and "page" aligned * Use lots of parallel IOs (high queue depth) * Do not put unrelated data in the same "page" A page used to be 4KB, SSDs are now switching to 8KB and will switch to 16KB later on. Just pick a reasonable size around that (16KB if you can do it will last you a while). Don't sweat the page multiples too much, the SSDs will most likely have to handle 4KB pages for a long while due to databases and such so they will keep some optimization around that size anyhow, it will make it easier for them if you use a larger size. I wouldn't heed any of the advice on single-threading, the biggest performance boost comes from parallelism and writes are anyway buffered by the SSD (a good SSD has a super-cap to have a good sized write cache).

baruch 12y ago

There is unfortunately no good place to do that. I work in an enterprise setting and get to talk to the ssd vendors and fish for details on how to best use their ssds and I still find it hard to get full information. Sometimes I wonder if there can even be a single compendium of knowledge about ssds. There are just so many moving parts in there that I doubt the ssd vendors themselves know what is really happening. Many times there are strange behaviors that we hit and then the vendors get to debug their ssds and explain new things about what just happened. One effect that I can attest to is that I know quite a bit about the ssd inner-workings (or at least how it shows to the outside world, never saw an ssd firmware source line) but it would be very hard for me to sit down and write something about all aspects. I can however answer questions when needed.

joshuacc 12y ago
> There are just so many moving parts I found this amusing in the context of SSDs versus spinning rust. :-D
- baruch 12y ago
  Indeed :-) If you really want to be pedantic, there are electrons moving in there so it is solid state but it has moving parts :-)

danielvinson 12y ago

You can't really optimize for SSDs in general. You CAN optimize for a specific brand/model/controller on a certain chipset. If an optimization in general is possible, you can be sure that the SSD manufacturer already is utilizing it in firmware on higher-end drives.

baruch 12y ago

Unless you are optimizing for a specific SSD with known quantities there is no real way to do that. The high-level optimizations are important: * Choose a good SSD * Read and Write in "page" multiples and "page" aligned * Use lots of parallel IOs (high queue depth) * Do not put unrelated data in the same "page" A page used to be 4KB, SSDs are now switching to 8KB and will switch to 16KB later on. Just pick a reasonable size around that (16KB if you can do it will last you a while). Don't sweat the page multiples too much, the SSDs will most likely have to handle 4KB pages for a long while due to databases and such so they will keep some optimization around that size anyhow, it will make it easier for them if you use a larger size. I wouldn't heed any of the advice on single-threading, the biggest performance boost comes from parallelism and writes are anyway buffered by the SSD (a good SSD has a super-cap to have a good sized write cache).