Math Nerds...I need help please

[leeland]

I am trying to come up with a simple dynamic formula to calculate a value based on a set ratio.


This is going to be used for an automation process in file management...essentially as follows.


I need to keep a certain amount of free space in a file(i.e. 20%)

Once the file free space hits the threshold I want to do the math to say how much I have to extend the file to return it to the 20% free threshold.

My simple brain came up with a basic formula, which isn't working out dynamically...

Any recommendations are appreciated.

 

[OOBradm]

Let T = current file size
Let U = current used space
Let P = ratio to keep free (ex: 0.2)

NewFileSize = Math.Max(U/(1.0 - P), T)

 

[OOBradm]

Or if you can write it as an if statement,

if ( (U/(1.0 - P)) > CurrentFileSize)
CurrentFileSize = (U/(1.0 - P))

 

[JTsyo]

I am trying to come up with a simple dynamic formula to calculate a value based on a set ratio.


This is going to be used for an automation process in file management...essentially as follows.


I need to keep a certain amount of free space in a file(i.e. 20%)

Once the file free space hits the threshold I want to do the math to say how much I have to extend the file to return it to the 20% free threshold.

My simple brain came up with a basic formula, which isn't working out dynamically...

Any recommendations are appreciated.

I don't know what you mean by dynamic. You just have to check the basic formula more often for it to be dynamic. At any point after you change the file size you want (total file size) = (actual size * 1.2). I'm guessing currently you are only checking in the beginning?

Another way would be to extend the file by 20% of the data added each time new data is added. (total file size)= (old file) + (new data) + (.2*new data size)

Not sure if you need to subtract too when data is deleted, keep that in mind.

 

[leeland]

Or if you can write it as an if statement,

if ( (U/(1.0 - P)) > CurrentFileSize)
CurrentFileSize = (U/(1.0 - P))

Thanks partner...I got around my issue for the most part using this logic...I brought the ratio out to the 1000's to tweak it a little bit but it worked just fine.

I was writing this into a T-SQL query so I had to use a CASE statement instead of an IF but it works all the same.


Thanks for taking the time to reply.


Lee