Hi Brad, Thanks for your reply.
Yes, I did the test after reboot. If I run same sql statement twice, I noticed that the second sql gives faster result. Do you know how to turn off file system cache on Win 7 64 bit? Best regards, Incedio --- In firebird-support@yahoogroups.com, Brad Pepers <brad@...> wrote: > > > 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 >
