Ive done alot of reading that mounting var/sessions and var/cache to ram will give a performance boost. However would this still be beneficial if I am using SSD?
closed as primarily opinion-based by brentwpeterson, 7ochem, pspahn, Amit Bera♦, Keyul Shah Jun 3 '15 at 0:51
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It's always better to put the data you want to cache in Ram memory as is faster than a SSD. RAM is much faster than SSD but volatile, that means if the power is gone then the data is lost.
Also Ram is not only faster but the OS uses it in a complete different way.
This is just to give an example but a tipycal DRAM has a transfer rate of approximately 2-20GB/s, whereas typical SSDs have a transfer rate of 50MB-200MB/s. So it's one to two orders of magnitude slower.
RAM is far more flexible and is truly random access -- any word, any time. By comparison, flash writes have to erase an entire block at a time before writing to it; and there are other problems that need to be dealt with such as wear leveling and bad blocks.
So you have to put a file system on top of SSD to deal with those issues. You can put a file system on top of DRAM (it is called a ramdisk), but you don't have to.