>>>>> "jam" == jam <[email protected]> writes:
jam> On Sunday 19 April 2009 10:00:03 [email protected] wrote: >> On Sunday 19 April 2009 00:16:35 [email protected] wrote: >> >> I've decided to increase the RAM on my home CentOS server. As best >> I >> can recall, the accepted wisdom is to have SWAP approx.~ 2 x >> RAM. Or >> was that approx.~ 50% of RAM? >> >> >> >> Can someone point me in the direction of an explicit tutorial on >> how >> I might go about increasing SWAP without destroying data on >> my other >> partitions please? >> >> >> >> Or if I'm actually upping the RAM, should I just not worry about >> it? >> >> >> >> Info I'm guessing would be relevant; >> > >> > Of course this is cockamany, urban myth, etc and typically you > >> increase RAM and need even less swap than before >> >> Actually, back in the day this was a good and solid guide, both for >> performance and safety reasons. Today, less so, but I don't think >> it is quite as laughable or untrue as you suggest. jam> From the days of my first system (PDP11, 100K RAM, 15MB disk) jam> till today I cannot see why this opinion is held. I first jam> encounted it as a RedHat recommendation. Pray wax lyrical ... Standard (i.e., Edition 7 and later) unices used to write all their memory into the swap partition on crash, along with some headers. Then when you booted the system, the early code would recognise that the swap partition was full of a memory image, and offer to dump it to tape (or, for Kodak Unix, to 8" floppies!). Then after you'd booted and fscked, you could load the image into a file, and use the crash(8) utility on it to find out why the kernel crashed. For all this to work, you needed a bit more swap than you had RAM --- and two times would always be enough (and it was a good enough rule of thumb that made its way into the SCO system administrator's course --- in the days when machine prices started coming down, and instead of a central system, companies were putting in small servers here there and everywhere; quite often the admin assistant or receptionist would be sent on a course to learn how to set up or administer the thing. I remember giving courses in 1986--8 and they were full of women who'd been told off to learn how to use and administer `the computer'. I taught them vi and troff (word processing) how to install, partition, and format discs, add users, use chmod, use printers, set up serial ports for terminals, etc (all the admin stuff) in three days!!! At least they could generally type. Niceties such as working out exactly how much swap you needed were way too complex, so we told them, twice your RAM) Peter C -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
