On 2011-10-27, at 7:56 PM, trskopo wrote: > Hi all, > > I just doing a little experiment to find out database performance on RAM vs > on Disk. > > I use WD SATA 2 Green, 64MB cache for testing. My RAM speed is about 35x > faster than disk. > > I have 2 databases (size is about 75 MB), one placed on a RAM and the other > on disk, then I run select sql for both databases > > SQL Statement finished about 47 seconds, on RAM and on disk. So there is no > significant performance between RAM and disk. > > Performance on RAM shows when doing backup or restore routine. > > So I wonder, could it be that there is no need for faster hardisk when using > firebird?
When you did your test, was it after a reboot? If not, then the operating system might well have been caching that 75 MB database file on disk in RAM so that is why the performance was the same. You have to be *really* careful in testing performance that what you're measuring is what you think you're measuring. Also note that on Windows Vista and 7 the operating system keeps track of the files you use often and will pre-load them into the file system cache in memory even if you haven't even used them yet. So even after a reboot if you give the operating system some time the file may be loaded into RAM even though you haven't even used it yet! You need to turn this feature off if you want to do accurate performance testing on Vista/7. -- Brad
