Linda Walsh <suse@tlinx.org> wrote:
Felix Miata wrote:
Once I partitioned a disk in 20 or 30 partitions, and tested speed on all of them. The faster region was about 1/3 of the disk. It was slower at the end of the disk than at the start; that I expected, but not that it would be faster at 1/3.
Confirmed via observation here, closer maybe to 25%, but clearly slower
#1 on http://fm.no-ip.com/PC/bench/Sysbench/resul603.txt looks like the only such doc I saved. Note on its #2 the difference between front and middle is very small. All others I checked at http://fm.no-ip.com/PC/bench/Sysbench/ are fastest at front. Most of these were done shortly after receiving a new HD, prompting to test to see what speed to expect. ISTR seeing it happen more than once though. Otherwise I don't think I'd have remembered it ever happening.
Just thought of something.
Did you go from the beginning of the first partition or the beginning of the disk?
Be default, or unless you've gone for DOS compatible partitioning, the first partition won't be track-aligned due to the boot sectors.
Then usually, people (or software) opts for nearest track for end of 1st partition, so further partitions are aligned.
It would make a slight difference, but the head would have to move over a track mid-read -- to read any track in the first partition, if such a situation were in place.
I know when I partitioned with fdisk, I had to toggle a flag to make sure it was dos compat, otherwise, I got the use of 200 and some odd more sectors out of the first partition.
Linda, It is time for you to enter the 21st century in respects to disk geometry. Back in the 80's and 90's CHS actually corresponded to physical reality. But LBA was introduced about 20 years ago because CHS was a pain. When disk sectors shrank to where more than 255 sectors per track became normal, the drive manufacturers just started lying when they reported the CHS geometry because 255 was the biggest reportable value and nobody cared enough at that point to fix the CHS standard. For at least the last decade the linear density of sectors is typically constant over the whole platter. Since you know circumference of a circle is PI * D, a track 3 inches from the center holds 3x the sectors as one 1 inch from the center. That means number of sectors per track isn't even a constant for a modern drive. That by the way is why start of the drive is faster than the end. The drives start at the outside edge, so for one revolution the head passes over a lot more sectors. The end of the drive is closer to the center, so it sees less sectors per revolution. And at least for now the rpms is kept constant, so the sectors per second speed is higher for the start of the drive. Anyway, if you think you have the ability to align partitions to tracks, you are simply mistaken. You can merely Fyi: both modern windows and linux align to 1MB boundaries with no concern how that aligns with tracks. Greg -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org