Disk Availability -- Does it decrease execution times

[deleted_user]

I ran into this problem today. Consider this
I have my datasets on F drive. All my programs fetch data from F drive. And the programs only recreate the datasets on F drive; no new datasets get created finally on F drive, but their sizes increase marginally every time the programs are run.
But SAS sits on C drive meaning my WORK directory is on C drive.

Will increasing the free disk space on F drive, decrease execution times of my programs? Please note that my programs use good amount of sorting and merging

Appreciate your help!
Message was edited by: srikanthdbn at Mar 22, 2007 7:35 AM

[prholland]

I have some questions which will affect my answer to your query:
(1) Where is your F drive? If it is not on your local PC then the network delays will affect your execution times much more than any shortage of disk space on the drive itself. On your local PC shortage of disk space may not affect on execution times, but are more likely to cause step failures if the disk becomes full.
(2) Lack of memory is more likely to affect execution times than lack of disk space. If your program requires more memory than is physically available, Windows will increase the virtual memory by using the disk-based swap file. Disk access is much slower than memory access, so execution times can be significantly increased.

Hope this helps.........Phil

[deleted_user]

Hi Phil,

Apologize for the late response

My F drive is on local PC. I never ran into step failures. I guess, this is an indication that the available disk space is good enough!!

Where does virtual memory disk-based swap take place. Does it happen on F or C (work) drive?
If it happens on C drive, then I think increasing free space on F drive does not any effect. What say?

I have 3.75GB of memory. The largest dataset I can think of occupies around 12GB(uncompressed). What could be the
approximate largest value of disk space required for virtual memory for sorting on by _All_ . (C or F drives??)

[prholland]

Your swap file could be located on any local drive, but is probably on the C drive. Assuming you are using Windows XP, you can find out where by looking in Control Panel > System > Advanced tab > Performance section > click Settings button > Advanced tab > Virtual Memory section > click Change button. The drives available are listed and the drive where the swap/paging file is located is shown here.

I don't recommend changing it, but knowing where it is gives you a better chance of avoiding it!!

.......Phil