How important is Random read/write 4 KB speed? A discussion about SSDs

I've recently bought an OCZ Agility 120 GB and installed it in my laptop (HP HDX16t). I bought this one over the Intel because it offered a better GB/$ ratio and I really wanted the extra space over the 80 GB Intel (and the 160 GB intel was out of the question due to price).

After a fresh Win7 64 bit install, the performance was truly great with some things and not as great as I was expecting with others. Not all things (like Firefox, for example) immediately SNAPPED up. So I downloaded and ran CrystalDiskMark and checked the data rates. They appear to be not quite as good as they appear in the Anandtech recent Intel X-25M G2 review. Speed was good for Sequential read/write and Random read/write 512KB was good too, but Random 4KB read/write was about 14MB/sec and 7.5 MB/sec, respectively. I understand these scores are MUCH better than a HDD, but according to reviews the Intel's are getting closer to 50MB/sec read, 35MB/sec write for the random 4KB test.

So my question is - How important IS the 4KB random test? There are actually some areas where the OCZ beats the Intel (like Sequential write and 512KB random write), so if these areas are just as important, maybe its worth keeping the drive. Should I keep the OCZ and just be happy with it, or return it in favor of the smaller drive even though it would make data storage a little uncomfortable?

Any thoughts?

In simple terms: You wouldn't notice the difference.

the only thing that I know of that defaults to 4kb blocks is an IBM nSeries, otherwise known as a NetApp box. 4kb is the ONLY block size you get, non-adjustable. IMO, 4kb blocks on a desktop OS is ridiculously undersized. most of your OS I/O requests are going to be 64 or 128kb blocks.

as Cyant said... you're not going to notice it... unless you somehow defined your block size on the SSD as 4kb... then you're screwed, and you need to nuke the drive config in the controller and redo it as 64 or 128kb blocks. otherwise, leave it alone.

Thanks, that certainly sets my mind at ease somewhat. I didn't change the block size at all - its just the default, whatever that is.

Maybe I'll stick with the OCZ then

From what I have read on OCZ's forums (yes, I know a bias source) most users would not notice the difference past 1-2MB/s in 4k random read/write. I am not sure if I believe that, but who knows maybe it is accurate.

Nevermind.

Wasn't the entire Anandtech SSD article about how 4kb write/read performance is by far the most important?

it was about how the erase was slower than the read/write

Adidas4275 said:

it was about how the erase was slower than the read/write

Click to expand...

I'm talking about the original article that compared the first OCZ Vertex to the Intel X25-m. They stated that the Intel was the clear winner because of far better random 4kb performance, which is the driving metric behind a "good" computing experience.

That was mostly vs mechanical HDs which thrash in small random IO and te JMicron controller which imitates a floppy in those circumstances. Anands recommendation for buying is to decide how much capacity you need and get whatever drive is cheapest that provides it instead of always getting an intel or indilinx drive. Both massively outclass mechanical drives and since each beats the other in different tests which is better is a tossup.