Date: Tue, 21 Oct 2003 04:07:34 +0000 From: "Matt Hanson" <[EMAIL PROTECTED]> Subject: RE: [LIB] How to calculate cylinder#s from sector#s?
Guess I'll cross-post to the list in case it's of any use to someone else down the line. Reply from the list message if you can.
David wrote:
Hanson wrote:Then I was going to created a logical/extended partition with the rest of the space, butfor some weird reason PM only reported about 20GB worth of space left.
Use the most current version. You may have to turn extended int13 bios access off since EZ-Drive is active and has taken over that role.
Well, I am using PM v8. After I used FDISK to creat one huge extended partition after the 3GB primary one... PM was then able to see the whole deal without playing with BIOS settings, which I hadn't thunk about.
I read through the info you sent, and I still don't see how you managed to determine the values for the cylinders for the hibernation area. I'm guessing you just experimented by making a partition straddling the 8.4GB barrier with PM, then used WinHex to see where the hibernation data lay, and then went back to PM, and sized the partition down a bit. And then probably repeated the process a few times, checking to see what PM reported for the partition to see what the range of cylinders was for an optimum hibernation partition. Yes?
Actually, I simply created a bootable partition that was 2GB. After EZ-Drive was installed, installed Windows 98 into that. Used a free disk space wiper to clear out the rest of the HD to zeros. Opened Notepad and wrote a unique text string such as "Librettos are cool!". hibernated, then unhibernated. Used WinHex to search the entire HD for "Librettos are cool!". When I found that, scrolled up and down in WinHex to determine where the hibernation data (non-zeros) was written. WinHex will tell you which /sectors/in the display you are looking at currently. Simply extended the start and end values by a few to be safe. Created the other partitions around that.
The problem there was that when I 1st used this method to set up my 20GB HDD last year, I didn't know how to use the start and finish sectors I was looking at to set anything up in PM. I used a mathmatical approach of proportionality to estimate the distance from the beginning of the HDD space in MBs to the beginning and end of the hibernation area, and then plugged them into PM. Then I went to Partition > Properties > Partition Info, looked at the cylinder #s, and then went back and tweaked the settings for partition size and position a few times, and repeated the 'hbernation & WinHex' process until I got the hibernation partition and small as possible, with a little more on each side just in case.
What I'm trying to do is understand the relationship between what I'm seeing in WinHex, which doesn't report info on cylinder (unless I'm missing something), and the value for cylinders reported in PM.
If you're using sectors, 1 sector = 512 bytes.
You can find out how many cylinders are on the HD through EZ-Drive.
When you know which sectors need to be marked off, [sector start] * 512 bytes = where on the HD you must start.
If you know there are, eg. 1024 cylinders on the HD and have a 20GB HD, then [sector starts] * 512 (from above) / 20GB * 1024 cylinders = approximate cylinder or cluster value you use.
Okay... I'll have to go into EZ-Drive and see what it reports for the number of cylinders.
Still... I'd still like to know just what the definition of a cylinder is, and how a position of a particular cylinder can be determined mathmatically by the specs from the manufacturer, and from WinHex data.
So if I know the start sector, I can multiply each by 512, and size the partitions before the hibernation partition up to a bit less than that value. Similarly I can take the difference between start and ending sectors, multiply by 512, and create a hibernation partition a bit larger than value. Sound right?
Yes.
Okay... great.
Notice that when you create any partition in Partition Magic, then Get INFO on that partition, the "Partition Info" tab will tell you exactly which starting and ending sectors are being used. You can use this as well.
Yeah... that was useful info the 1st time I went through this.
Thanks David!
Matt
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