Reserved System Space

[2z]

Posted by dealer
2z, we,'e had this conversation before.

And still we disagree

Posted by dealer
seek time is deminished whem the information is in the area that the heads reside the majority of the time, and this means towards the midddle of your most accesed data, and not at the beginning of the disc, where the heads are at the beginning of the day

the heads park along the inner tracks me thinks
seek time is diminished when the information is spread throuhgout the disk
if all the data is at the front of the disk then the heads never need to do a full sweep .

Posted by dealer
Putting a file at the beginning of the HD optimizes transfer time, but hurts seek time, and the cost in seek time is far greater than the gain in transfer time. In other words, it's a net loss.

Transfer time is everything

seek time needs to be measured with specialist software to see the minute differences

transfer time is

how long it takes to load the next level in a game

how long it takes to copy a big file

these operations can vary by minutes not nanoseconds

in other words a net gain

 

[Perris Calderon]

sorry 2z, seek time absolutely dominates transfer time.

I'll get back to that point, but I must address a point that slipped my attenation;

Advantage #1: A hard drive containing multiple partitions allows you to *lower* your drive's effective access time, providing you with a more responsive system.

If you create a partition at the outer/leading edge of your drive (*1), and install your operating system & applications there .. and use the inner/slower parts of the disk for storing files that don't require access during normal system operating (i.e. downloads, drivers, back-ups, Ghost images, etc.) .. you'll limit/restrict your drive's seeks to the fastest part of the drive.

W hen there is no information that is being accesed, of course, the beginnng of the drive will give the best performance, but when there is information being accesed, it's obvious the seek time will be reduced if the arm is already in position.

now, partitioning does not reduce seek time, it increases seek time, as the arm has to travel from partition to partition for files that are accessed in common practice.

with a sngle partition, these files will be optiomized, and closer together.

an obvious performance hit if you are using seek time as a reason to partition, no, seek time is a reason not to partition

 

[2z]

Posted by dealer
now, partitioning does not reduce seek time, it increases seek time, as the arm has to travel from partition to partition for files that are accessed in common practice.

thats why you previously recommened that the OS & the apps be installed to same partition

and why I also posted

Posted by me
If you create a partition at the outer/leading edge of your drive (*1), and install your operating system & applications there .. and use the inner/slower parts of the disk for storing files that don't require access during normal system operating (i.e. downloads, drivers, back-ups, Ghost images, etc.) .. you'll limit/restrict your drive's seeks to the fastest part of the drive.

therefore seek time is longer an issue

I rest my case

 

[Perris Calderon]

ok, now seek time vs. transfer time;

It is true that, given zone bit recording, the actual transfer rate to the media is faster at the beginning of the drive -- but the actual transfer time to the media is the smallest factor in total disk IO rate; seek time is the largest.

The reality of how disks are actually used is very different then simple transfer time quality. Remember that the Windows NT family usually does disk IO, in chunks no larger than 64 Kbytes at a time. OK, the "transfer" part of a 64 Kbyte transfer on a common drive would be 1.7msec, 2 msec, and 3 msec at the beginning, middle, and end of the drive, respectively.


But! It has a spec'd average seek time of 8.7 msec. That's the average of all possible seeks, shortest (one cylinder) to longest (all cylinders).

now, this most certainly affects performance in actual use of the disk. In fact the seek time is part of the total time to perform each and every IO. Some seeks are longer, some shorter, but almost every IO in the real world is going to include a seek. Average time per seek, almost 9 msec.

 

[Perris Calderon]

ah, I posted before I read your last post, and I agree with that post.

however, and back on point, where you say "me thinks the arm rests at the beginning of the disc the majority of the time.

here, we would agree if an individual hardly uses hardrive activity at all, however, obviously, if the individuals hardrive is active, seek time will be resovled in quicker fassion towards the middle of his hardrive activity, so, in essence, we are agreeing, that for some users, the beginning of the disc for most accesed files, for other users, the middle of the information for most accesed files.

i'm guessing this is one reason the mft is placed towards the middle, and not directly in the middle of information.

your previous post is a good one

your case was rested well

good, this conversation

good to see you

 

[ghayes]

"So in response to this problem M$ created NT5 with the MFT now created next to a free zone SOOOOOOO BIG fragmentation of the MFT is no longer an issue."

The default size of the MFT Reserved Zone has NOT changed from NT4 through WinXP - it remains 12.5% of the parition and is adjacent to the $MFT - regardless of where the $MFT resides (beginning, middle, end of partition).

Actually, with Win2k and WinXP the size of the MFT Reserved Zone can actually end up being smaller than the Reserved Zone in NT4.

With NT4, the MFT Reserved Zone is always a fixed size - 12.5% of the drive (by default). With Win2k/WinXP, the MFT Reserved Zone is dynamically created every the the partition is mounted and goes from the beginning of the $MFT to the first non-free cluster (up to a default max of 12.5% of the drive) ). As soon as the file system places a file inside of the $MFT Reserved Zone, the next time the partition is mounted, the MFT Reserved Zone size will be smaller than the 12.5%.

- Greg/Raxco Software