Thought experiment: HDD with flash read-cache?

[onex]

do you have any idea of work load usage patterns in regard to file size and/or preferred block size for a raid array of different setups?

E:
found something on AT,
light workload -

The light workload is composed of 37,501 reads and 20,268 writes. Over 30% of the IOs are 4KB, 11% are 16KB, 22% are 32KB and approximately 13% are 64KB in size. Less than 30% of the operations are absolutely sequential in nature. Average queue depth is 6.09 IOs.

heavy workload -

consists of 128,895 read operations and 72,411 write operations. Roughly 44% of all IOs were sequential. Approximately 30% of all accesses were 4KB in size, 12% were 16KB in size, 14% were 32KB and 20% were 64KB. Average queue depth was 3.59.

gaming workload -

gaming workload is made up of 75,206 read operations and only 4,592 write operations. Only 20% of the accesses are 4KB in size, nearly 40% are 64KB and 20% are 32KB. A whopping 69% of the IOs are sequential, meaning this is predominantly a sequential read benchmark. The average queue depth is 7.76 IOs.

i've been saying to kevikev member here not long ago that usual QD won't normally pass 10, so it seems right.

now we might be able to get an idea on typical server usage, sadly AT ain't doing any server benchmark with pre-defined work-load for every setup as it does with mainstream patterns,
we'll need to find out the % of hot-files usage in different dedicated machines in order to be able to estimate such "hybrid" feature potential.

iv'e been asking anand few weeks back on the software he uses for he's benches, yet he says it's propriety and NDA'd.
we came up with Xperf from WPT (win performance tool) as a testing tool that might bring out some profound information on disk usage, it's the only one i found, yet havn't had the chance to test it.
darn, i wish i could grab that one he uses, a specialized software that should be especially designed for drive performance analysis.
so much crap in the markets and un-professional tools ,
it seems they don't give independent research any chance.