Re: How manu swap ?
* Disk space is cheap. 16G of swap costs what? 15G of 15,000 RPM SCSI not mentioning IDE disks, on 4GB RAM+6 SATA disk system i allocated 2GB swap on each disk. most of the time little is used, but when it will be needed - it is ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
Dan Nelson wrote: In the last episode (Jan 16), Albert Shih said: Hi all I known it's classic question. Long time ago when I install a FreeBSD x86 32 bits when I have N Go of Ram the installer take 2xN Go for the swap partition. Now I just install two machine with FreeBSD amd64 version with 8Go of Ram and FreeBSD installer take 4 Go of swap. Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? When was the last time you saw your swap partition with more than 2GB in use? On an 8GB system, you probably will either never have enough processes to require swapping at all, or you will have one or two processes so big that if they ever swap, it's a sign you need more RAM, not more swap :) In systems with that much RAM, swap is pretty much only used for crashdumps, and with minidumps enabled by default, you don't need much. On small systems, the 2x-swap rule was because once you allocated enough processes to require that much swap, you were pretty much thrashing your system anyway I've read that the VM system in FreeBSD is optimized such that if you do start swapping it'll work best if your swap space is at least 2x RAM. Is that still valid on recent releases of FreeBSD? -- Bruce Cran ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
On Wed, Jan 16, 2008 at 10:28:06AM -0600, Dan Nelson wrote: > In the last episode (Jan 16), Albert Shih said: > > Hi all > > > > I known it's classic question. > > > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go > > of Ram the installer take 2xN Go for the swap partition. > > > > Now I just install two machine with FreeBSD amd64 version with 8Go of > > Ram and FreeBSD installer take 4 Go of swap. > > > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? > > When was the last time you saw your swap partition with more than 2GB > in use? On an 8GB system, you probably will either never have enough > processes to require swapping at all, or you will have one or two > processes so big that if they ever swap, it's a sign you need more RAM, > not more swap :) In systems with that much RAM, swap is pretty much > only used for crashdumps, and with minidumps enabled by default, you > don't need much. On small systems, the 2x-swap rule was because once > you allocated enough processes to require that much swap, you were > pretty much thrashing your system anyway. Don't forget that the system uses swap space to do paging too and that frequently used processes can end up in swap and be run from there faster than from regular disk. But, yes, the 2X rule was generally a combination of space for crash-dump plus room to run more than memory can hold. jerry > > -- > Dan Nelson > [EMAIL PROTECTED] > ___ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "[EMAIL PROTECTED]" ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
In response to Albert Shih <[EMAIL PROTECTED]>: > Le 16/01/2008 à 10:28:06-0600, Dan Nelson a écrit > > In the last episode (Jan 16), Albert Shih said: > > > Hi all > > > > > > I known it's classic question. > > > > > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go > > > of Ram the installer take 2xN Go for the swap partition. > > > > > > Now I just install two machine with FreeBSD amd64 version with 8Go of > > > Ram and FreeBSD installer take 4 Go of swap. > > > > > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? > > > > When was the last time you saw your swap partition with more than 2GB > > in use? On an 8GB system, you probably will either never have enough > > processes to require swapping at all, or you will have one or two > > processes so big that if they ever swap, it's a sign you need more RAM, > > not more swap :) In systems with that much RAM, swap is pretty much > > only used for crashdumps, and with minidumps enabled by default, you This is really a pretty narrow view of things. * Swap _can_ be used to extend a systems usability beyond what it was originally designed for. If you don't exceed the physical RAM by too great a margin, allowing a few little-used processes to page out while heavy use processes use all available memory is not a big performance hit. * The idea that an 8G system will never use all that RAM is laughable to me. I can easily create applications that eat up 8G of RAM, legitimately. * In the event that something unexpected happens, having a lot of swap can save your ass by causing the system to slow down instead of kill processes. * Disk space is cheap. 16G of swap costs what? 15G of 15,000 RPM SCSI hard drive space costs $40 -- not much for piece of mind. * Of course, the crash dumps that are mentioned. I agree, though, that swap isn't what it used to be. Nobody uses it as supplemental RAM any more as far as I can tell. It's pretty much just a safety net nowadays. -- Bill Moran http://www.potentialtech.com ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
none if your ram will always fit all apps (with 8GB is more than likely), or at least size of your memory, more if needed. but you can't give too much swap! ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
Le 16/01/2008 à 10:28:06-0600, Dan Nelson a écrit > In the last episode (Jan 16), Albert Shih said: > > Hi all > > > > I known it's classic question. > > > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go > > of Ram the installer take 2xN Go for the swap partition. > > > > Now I just install two machine with FreeBSD amd64 version with 8Go of > > Ram and FreeBSD installer take 4 Go of swap. > > > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? > > When was the last time you saw your swap partition with more than 2GB > in use? On an 8GB system, you probably will either never have enough > processes to require swapping at all, or you will have one or two > processes so big that if they ever swap, it's a sign you need more RAM, > not more swap :) In systems with that much RAM, swap is pretty much > only used for crashdumps, and with minidumps enabled by default, you OK. I never need this because FreeBSD never crashwell more specific : I never see FreeBSD crash and event it's crash I not qualify to use crashdumps ;-) > don't need much. On small systems, the 2x-swap rule was because once > you allocated enough processes to require that much swap, you were > pretty much thrashing your system anyway. OK. Thanks for your answer. Regards. -- Albert SHIH Observatoire de Paris Meudon SIO batiment 15 Heure local/Local time: Mer 16 jan 2008 17:35:44 CET ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
Le 16/01/2008 à 11:18:57-0500, Jerry McAllister a écrit > On Wed, Jan 16, 2008 at 04:04:54PM +0100, Albert Shih wrote: > > > Hi all > > > > I known it's classic question. > > > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go of Ram > > the installer take 2xN Go for the swap partition. > > > > Now I just install two machine with FreeBSD amd64 version with 8Go of Ram > > and FreeBSD installer take 4 Go of swap. > > > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? > > H. I doubt that it is a "bug" per se. I wonder if there is > a maximum size for swap compiled in somewhere. Is your system set > up correctly to actually access all 8GB of ram? Yes... Mem: 8064K Active, 6076K Inact, 68M Wired, 8896K Buf, 7829M Free Swap: 4096M Total, 4096M Free and the second machine Mem: 12M Active, 561M Inact, 322M Wired, 12K Cache, 214M Buf, 15G Free Swap: 4096M Total, 4096M Free Regards. JAS -- Albert SHIH Observatoire de Paris Meudon SIO batiment 15 Heure local/Local time: Mer 16 jan 2008 17:34:40 CET ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
In the last episode (Jan 16), Albert Shih said: > Hi all > > I known it's classic question. > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go > of Ram the installer take 2xN Go for the swap partition. > > Now I just install two machine with FreeBSD amd64 version with 8Go of > Ram and FreeBSD installer take 4 Go of swap. > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? When was the last time you saw your swap partition with more than 2GB in use? On an 8GB system, you probably will either never have enough processes to require swapping at all, or you will have one or two processes so big that if they ever swap, it's a sign you need more RAM, not more swap :) In systems with that much RAM, swap is pretty much only used for crashdumps, and with minidumps enabled by default, you don't need much. On small systems, the 2x-swap rule was because once you allocated enough processes to require that much swap, you were pretty much thrashing your system anyway. -- Dan Nelson [EMAIL PROTECTED] ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: How manu swap ?
On Wed, Jan 16, 2008 at 04:04:54PM +0100, Albert Shih wrote: > Hi all > > I known it's classic question. > > Long time ago when I install a FreeBSD x86 32 bits when I have N Go of Ram > the installer take 2xN Go for the swap partition. > > Now I just install two machine with FreeBSD amd64 version with 8Go of Ram > and FreeBSD installer take 4 Go of swap. > > Is a bug in the installer or now FreeBSD don't need 2xRam of swap ? H. I doubt that it is a "bug" per se. I wonder if there is a maximum size for swap compiled in somewhere. Is your system set up correctly to actually access all 8GB of ram? Anyway, you can get by with less than 2Xram. It depends a lot on what you are running and how many processes.I would like to have more than 1Xram though - at least 1.25xram. So with 8GB, I would want to have at least 10GB swap. Hopefully someone else will be able to answer with something more specific and helpful. jerry > > Regards. > > -- > Albert SHIH > Observatoire de Paris Meudon > SIO batiment 15 > Heure local/Local time: > Mer 16 jan 2008 16:03:16 CET > ___ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "[EMAIL PROTECTED]" ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
