Re: Informix database - memory recommendations

Billy Wheeler <billy@west.co.za> wrote: > On 26 Aug 98 at 13:06, SHANMUGH NATARAJAN wrote: >> We have a 1.1 GB database on an HPUX machine. >> One of our clients is interested in finding out >> the optimal or recommended physical mem size required >> for a database of this size. >> >> I called customer service and they didnt have an answer to that. >> They talked about monitoring the swap space to see if you need more >> memory. But that is not acceptable to the client and they want to >> know the official recommended size. >> >> any statistics on this kinda stuff ?? > How about 1.1GB + size of O/S in RAM + (say) 20%? Which reminds me of an (admittedly off-topic) story. I work for a telephone company. They bought an HP-9000 of some variety, and used the kernel that shipped with it, about 2Gb of RAM or so. Few weeks into production, they were getting horrible performance out of the database. After spending a couple of weeks profiling the apps and the database and the OS itself, they were stumped an called HP. Said HP, "Oh, that kernel allocates .75Gb of RAM as swap space. Recompile the kernel, turning of the RAM disk, and you'll be fine." Never mind the brain damage involved in allocating system RAM as swap, my "colleagues" debated for three days about whether or not to "risk" this change - they feared that returning the RAM to the OS (and thus to the database) would hamper performance... Epilogue: the app runs like a rocket with no RAM allocated to swap. Kurt