Andy Burns wrote:
Now I'm scratching my head too,
OK, having looked at hdparm man page for -T
"This displays the speed of reading directly from the Linux buffer cache without disk access. This measurement is essentially an indication of the throughput of the processor, cache, and memory of the system under test. If the -t flag is also specified, then a correction factor based on the outcome of -T will be incorporated into the result reported for the -t operation."
I always though -T just repeatedly read one sectore from disk's on baord cache repeatedly, clearly I have always been wrong, that is what "-t" does :-(
I thought "-t" read a file large enough to overflow the onboard disk cache, so actually I'm pleased my dmrebuild test does actually give the same speed.
And the difference in your 2228MB/s, my 4456MB/s and your friends 1800MB/s are down to motherboard/cpu/memory, mine is P4 630 with dual DDR2 667MHz