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Path: sserve!manuel!munnari.oz.au!hp9000.csc.cuhk.hk!uakari.primate.wisc.edu!caen!destroyer!uunet!math.fu-berlin.de!unidui!du9ds3!veit From: veit@du9ds3.uni-duisburg.de (Holger Veit) Newsgroups: comp.unix.bsd Subject: Re: stock 0.1 swap not enough. Keywords: swap Message-ID: <veit.712998619@du9ds3> Date: 5 Aug 92 07:10:19 GMT References: <BsDzMo.1ru@chinet.chi.il.us> <BsFMoo.EvF@obiwan.uucp> <1992Aug4.162010.16364@mks.com> Sender: @unidui.uni-duisburg.de Reply-To: veit@du9ds3.uni-duisburg.de Organization: Uni-Duisburg FB9 Datenverarbeitung Lines: 66 In <1992Aug4.162010.16364@mks.com> fredw@mks.com (Fred Walter) writes: >bob@obiwan.uucp (Bob Willcox) writes: >>randy@chinet.chi.il.us (Randy Suess) writes: >>> Well, I now have proof that the stock 5 meg swap partition >>> created with the 0.1 install disk is not enough. I added >>> a second disk and gave it another 5 megs of swap (I have >>> 8 megs memory) using swapon. >> >>How does one go about increasing the swap size when you only have a >>single disk? Is there a way to do this without re-installing? >No, you'll have to re-install. What I plan on doing (once my system is >more stable) is backing up my system with cpio, then using the Fixit disk >(and an editted /etc/disktab on the Fixit disk that has a correct swap size >entry) to re-disklabel my primary hard disk, re-format my partitions and then >restore from tape. >I've seen several formulas for calculating the correct amount of swap. > - one person said 2*physical_memory*1.1 > - one person said 2*physical_memory*1.5 >So, which is it ? I'd rather not waste more harddisk space than necessary on >a too-big swap partition (I have 12 meg RAM; 2*12*1.1=26.4; 2*12*1.5=30) >because I'm currently running without a swap partition and my system hasn't >seemed to need one. But I want to run X386 and those binaries are *hugh* so >I'll need some swap space. (And more memory, and more hard disk space...) > fred >-- >Disclaimer: everything I write is my *personal* opinion and does not represent >or reflect the opinion of the company which employs me. As already someone mentioned: The request for a formula depending on available RAM is incorrect. The formulae N*phys_mem is a rule of thumb and may or may not fit your requirements. I also read in the SUNOS Manuals to use 2*physmem+10%, but this has been calculated (or guessed?) for an average usage profile. The swap space depends at least on: - The number of processes you want to run - the space requirement these processes have (you know "EMACS = eight megabytes and continuously swapping" :-) ) BTW: on our Sun's we have some testpattern generation software which has virtual space requirements of > 100 MB - the number of users who use the system (notice that each window in X11 counts as a single user, again a rule of thumb) - the number of simultaneous network connections - the disk throughput (to make file access faster, you must add FS cache space, this reduces available main memory, the system starts paging and swapping earlier) - ... - ... There are more dependencies, look into a good book on operating systems design. The standard 5 MB swap space are sufficent in the environment of the files of the bindist, provided you use your PC as a "work station" (not multi-user machine). X11 should have at least 16 to 32 MB (independently of how much RAM you have, but you should not even think of X11 with less than 8 MB RAM). My $0.02. Holger -- | | / Holger Veit | INTERNET: veit@du9ds3.uni-duisburg.de |__| / University of Duisburg | BITNET: veit%du9ds3.uni-duisburg.de@UNIDO | | / Dept. of Electr. Eng. | "No, my programs are not BUGGY, these are | |/ Inst. f. Dataprocessing | just unexpected FEATURES"