Coming back to your comment on raw device. I think if I replace read operations with writes and do a Fsync() call right after, then I am sure that I am getting raw access there. Also with hdparm, one...
At the application level page size is an important concept, it's the unit of interaction with the disk. Imagine a database system requesting a record A, it'd be completely inefficient to only read...
Alright, I get your point. I though that using /dev/sdb1 moves to position 0 :wall:
AFAIK hdparm only gives you the speed of the disk and not the time of reading a given amount of data.
Why is read-ahead a problem since above is only a 512bytes read, all it takes is normally positioning the drive head .. Then if the cache is the reason, it should affect the file as well, but I am...
I am trying to measure the speed of reading a given block size using the dd command. However depending on which input I use: a regular file (on the same device) or /dev/sdb1, I get some really...