Hi All, This is out of the topic question, but I''m hoping that you can help me. If for example I''m going to install a Fedora 4 64-bit with 8 to 12 Gig of physical memory, how much swap file of directory do I need to create? Thank you very much, Wennie
hi wennie, On Mon, 2006-03-20 at 10:44 +0300, wlagmay@yanbulink.net wrote:> Hi All, > > This is out of the topic question,yep.> but I''m hoping that you can help me. If for > example I''m going to install a Fedora 4 64-bit with 8 to 12 Gig of physical > memory, how much swap file of directory do I need to create?red hat suggests 3x physical memory, therefore, 24 to 36 gigs of swap. you have a lot of memory. cheers charles
Dnia poniedziałek, 20 marca 2006 08:44, wlagmay@yanbulink.net napisał(a):> Hi All, > > This is out of the topic question, but I''m hoping that you can help me. If > for example I''m going to install a Fedora 4 64-bit with 8 to 12 Gig of > physical memory, how much swap file of directory do I need to create?Do you really need any swapspace? Are you sure you will have enough programs running to eat all the memory you have? -- | pozdrawiam / greetings | powered by Trustix, Gentoo and FreeBSD | | Kajetan Staszkiewicz | jabber,email: vegeta () tuxpowered net | | Vegeta | IMQ devnames: http://tuxpowered.net | `------------------------^----------------------------------------''
wlagmay@yanbulink.net wrote:> > Hi All, > > This is out of the topic question, but I''m hoping that you can help me. If for > example I''m going to install a Fedora 4 64-bit with 8 to 12 Gig of physical > memory, how much swap file of directory do I need to create? > > Thank you very much, > > WennieWennie, You seem to think that the amount of physical RAM should have something to do with the amount of swap space. If so, that is wrong. Even with huge, and 8 gigs of RAM is huge, amounts of RAM, you need a dedicated swap partition. Don''t believe those who say you don''t. The size of the swap partition should be at least 512 megs. The maximum should normally be no more than 2 gigs. I like to spread this out over 4 disks. My setup creates a partition on each of the 4 hard drives in my system and then /etc/fstab has an entry for each partition that says /dev/hd# swap swap defaults,pri=1 0 0 -- gypsy
Off Topic I am not a swap fan these days. I am not to sure it''s really that necessary. If the system has adequate memory for the applications and task it will be doing. Most times there will be little to no swap used ever. The more memory, the less likely you will ever swap. And if you do it''s very small amounts. Any way you look at it swapping is bad. You are substituting one of the slowest components for one of the fastest. Either way swapping kills performance. Sure it could be the difference of out of memory, and apps, machine crashing, halting etc. Rare. Most times it''s a hit in performance not needed. Those rules of thumb for swap size vs ram size is only relevant if you have small amounts of ram. A system these days needs a min of 512, either physical or combo, swap and physical. Once you top 512MB of physical memory. Your needs for swap start diminishing. 1GB or more of ram, and hardly the need for any swap. At that point I tend to use 256-512Mb just to be safe. However I have seen years go by on some servers, with little to no swapping. So I max out on most machines at 256MB swap these days. IMHO swapping is bad. If you are swapping more than a 10-20MBs, more than likely you are best off to get some more ram. Unless that''s not an option then maybe another machine. When you do swap, things slow down, so I just seen no reason in it. Granted it was needed for the low mem systems of yester year. These days you can get a 512MB-1GB stick of ram for $50 or so. Hardly relevant any more. I have been toying around with getting rid of swap all together in some of my machines. When I experimented on a core NAS server. Only times I would have issues, was every now and then during heavy Gentoo updated/compiling. But not always, and never show stoppers. But the jury is still out for no swap here. -- Sincerely, William L. Thomson Jr. Obsidian-Studios, Inc. http://www.obsidian-studios.com
hi all, woops forgot -- that whole thing about maximum swap partition size :-/ yikes -- still a ton of memory :-) cya charles -- "simplified chinese" is not nearly as easy as they would have you believe ... a superlative oxymoron" --anonymous
gypsy wrote:> Even with huge, and 8 gigs of RAM is huge, amounts of RAM, you need a > dedicated swap partition. Don''t believe those who say you don''t.On the contrary. I run many systems without any swap at all. What you get by using swap is (from a very simplified point of view) that if you use up all memory, instead of the programs crashing, the system gets "slower" (but keeps running). Whether to use swap or not depends on what you''re doing with your computer.> gypsyYours sincerely, Peter -- http://www.shurdix.org - Linux distribution for routers and firewalls
gypsy schrieb:> The size of the swap partition should be at least 512 megs. The maximum > should normally be no more than 2 gigs.IIRC the 2 GB limit for swap partitions on i386 was lifted a few years ago. Regards, Carl-Daniel -- http://www.hailfinger.org/
On 3/20/06, Peter Surda <surda@shurdix.com> wrote:> > gypsy wrote: > > Even with huge, and 8 gigs of RAM is huge, amounts of RAM, you need a > > dedicated swap partition. Don''t believe those who say you don''t. > On the contrary. I run many systems without any swap at all. > > What you get by using swap is (from a very simplified point of view) > that if you use up all memory, instead of the programs crashing, the > system gets "slower" (but keeps running). Whether to use swap or not > depends on what you''re doing with your computer.I disagree in the point that you necessary needs swap. With that amount of RAM, it''s not needed making any swap of any size. I don''t think it''ll use all of these. By the way, there are some ways to use all that RAM so I suggest to put 512 MB of swap o 1 Gig, no more. This is by the fact that, if in anytime the systems gets out of RAM, swapping some low prio proceses will decide wich threads must stop without sacrifying any important data. -- Atentamente, Carlos. ------------------------------- LTIM Member - http://ltim.uib.es BkP Staff (Servidores, Gamer Area, Tesorean) - http://www.balearikus-party.org _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
Thanks to all, but to be more particular, Im going to use the machine with 8 or 12 Gig of physical memory for squid caching, and we all know that caching consumes to much memory. Our objective actually is to cache the most popular pages on the memory so that it will be faster to access by the clients. so far there are 3 ideas, 1st no swap dir at all, 2nd physical memory multiply by 2 or 3 and the 3rd one creating a swap with 512 MB to 1 Gig. On my scenario, wherein im going to use the system for caching, which one is more applicable? Thanks, Wennie Quoting Carlos Blanquer <relayito@gmail.com>:> On 3/20/06, Peter Surda <surda@shurdix.com> wrote: > > > > gypsy wrote: > > > Even with huge, and 8 gigs of RAM is huge, amounts of RAM, you need a > > > dedicated swap partition. Don''t believe those who say you don''t. > > On the contrary. I run many systems without any swap at all. > > > > What you get by using swap is (from a very simplified point of view) > > that if you use up all memory, instead of the programs crashing, the > > system gets "slower" (but keeps running). Whether to use swap or not > > depends on what you''re doing with your computer. > > > I disagree in the point that you necessary needs swap. With that amount of > RAM, it''s not needed making any swap of any size. I don''t think it''ll use > all of these. > By the way, there are some ways to use all that RAM so I suggest to put 512 > MB of swap o 1 Gig, no more. > This is by the fact that, if in anytime the systems gets out of RAM, > swapping some low prio proceses will decide wich threads must stop without > sacrifying any important data. > > > > > -- > Atentamente, > Carlos. > ------------------------------- > LTIM Member - http://ltim.uib.es > BkP Staff (Servidores, Gamer Area, Tesorean) - > http://www.balearikus-party.org >
wlagmay@yanbulink.net said:> > Thanks to all, but to be more particular, Im going to use the machine with 8 > or > 12 Gig of physical memory for squid caching, and we all know that caching > consumes to much memory. Our objective actually is to cache the most popular > pages on the memory so that it will be faster to access by the clients. > > so far there are 3 ideas, 1st no swap dir at all, 2nd physical memory > multiply > by 2 or 3 and the 3rd one creating a swap with 512 MB to 1 Gig. On my > scenario, wherein im going to use the system for caching, which one is more > applicable?First, always use swap. The only common reason to choose not to use swap under Linux is on a workstation where the user believes VM pressure is causing unwanted latency for interactive operations. This scenario is easily resolvable with tunable nobs for the Linux 2.6 VM and its entirely unnecessary to avoid creating a swap partition. As you''ve discovered, with 12GB of RAM using a 2 or 3 multiply rule is hardly reasonable. Ideally you will pick a value based on testing your workload against the actual machine in question. Personally, I rarely allocate more than 4GB of swap and never less than 512M with today''s large disks. If you''re worried about performance, you can stripe swap over multiple disks or disk arrays. Granted, you should never heavily be in swap, but if the circumstance arises it allows you to recover in some fashion. It''s the difference between a dead machine and a recoverable one. These days, I''d suggest a multiplier of simply 1, 0.5, or 0.25 for creating swap. Or did you _really_ need that 4-12GB of disk space for something more important than increased stability and availability of the machine in question? (If the answer is _yes_, buy _more_ disk.)
On 3/21/06, wlagmay@yanbulink.net <wlagmay@yanbulink.net> wrote:> > > Thanks to all, but to be more particular, Im going to use the machine with > 8 or > 12 Gig of physical memory for squid caching, and we all know that caching > consumes to much memory. Our objective actually is to cache the most > popular > pages on the memory so that it will be faster to access by the clients.I haven''t used Squid, but I thought that Squid uses Hard Disk space to caching. Maybe you can use RAM, but in Squid config you must specify what quantity of hard disk memory and how much time it can store the cached info. so far there are 3 ideas, 1st no swap dir at all, 2nd physical memory> multiply > by 2 or 3 and the 3rd one creating a swap with 512 MB to 1 Gig. On my > scenario, wherein im going to use the system for caching, which one is > more > applicable?I think 1 Gig is sufficient. Relaying on the fact that you''ll use your hard drive to caché all the squid info. Anyway, 1 Gig is the right option in my view. -- Atentamente, Carlos. ------------------------------- LTIM Member - http://ltim.uib.es BkP Staff (Servidores, Gamer Area, Tesorean) - http://www.balearikus-party.org _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
On 3/21/06, Jason Boxman <jasonb@edseek.com> wrote:> > wlagmay@yanbulink.net said: > > > As you''ve discovered, with 12GB of RAM using a 2 or 3 multiply rule is > hardly reasonable.Sorry? That''s a 36 GB swap ( 12 x 3 )? So much memory at all. Ideally you will pick a value based on testing your workload against the> actual machine in question. Personally, I rarely allocate more than 4GB > of > swap and never less than 512M with today''s large disks. If you''re worried > about performance, you can stripe swap over multiple disks or disk arrays.That''s right. -- Atentamente, Carlos. ------------------------------- LTIM Member - http://ltim.uib.es BkP Staff (Servidores, Gamer Area, Tesorean) - http://www.balearikus-party.org _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
If the machine will be used only for squid, I suggest you create no more than 1GB of swap, just in case the physical memory runs out. You can play with the cache_mem setting in squid.conf and see what is the maximum value with which it doesn''t use swap-space (after all what you seek is cache speed).> > Thanks to all, but to be more particular, Im going to use the machine with > 8 or > 12 Gig of physical memory for squid caching, and we all know that caching > consumes to much memory. Our objective actually is to cache the most > popular > pages on the memory so that it will be faster to access by the clients. > > so far there are 3 ideas, 1st no swap dir at all, 2nd physical memory > multiply > by 2 or 3 and the 3rd one creating a swap with 512 MB to 1 Gig. On my > scenario, wherein im going to use the system for caching, which one is > more > applicable? > > > Thanks, > > Wennie > > Quoting Carlos Blanquer <relayito@gmail.com>: > >> On 3/20/06, Peter Surda <surda@shurdix.com> wrote: >> > >> > gypsy wrote: >> > > Even with huge, and 8 gigs of RAM is huge, amounts of RAM, you need >> a >> > > dedicated swap partition. Don''t believe those who say you don''t. >> > On the contrary. I run many systems without any swap at all. >> > >> > What you get by using swap is (from a very simplified point of view) >> > that if you use up all memory, instead of the programs crashing, the >> > system gets "slower" (but keeps running). Whether to use swap or not >> > depends on what you''re doing with your computer. >> >> >> I disagree in the point that you necessary needs swap. With that amount >> of >> RAM, it''s not needed making any swap of any size. I don''t think it''ll >> use >> all of these. >> By the way, there are some ways to use all that RAM so I suggest to put >> 512 >> MB of swap o 1 Gig, no more. >> This is by the fact that, if in anytime the systems gets out of RAM, >> swapping some low prio proceses will decide wich threads must stop >> without >> sacrifying any important data. >> >> >> >> >> -- >> Atentamente, >> Carlos. >> ------------------------------- >> LTIM Member - http://ltim.uib.es >> BkP Staff (Servidores, Gamer Area, Tesorean) - >> http://www.balearikus-party.org >> > > > > > _______________________________________________ > LARTC mailing list > LARTC@mailman.ds9a.nl > http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc >-- Anton Glinkov network administrator
I agree, 1-2GB of swap is good choice from my experience. I don''t think you should run without swap at all - there usually is something OS can push to swap and free some ram. On Wednesday 22 March 2006 17:56, Anton Glinkov wrote:> If the machine will be used only for squid, I suggest you create no more > than 1GB of swap, just in case the physical memory runs out. You can play > with the cache_mem setting in squid.conf and see what is the maximum value > with which it doesn''t use swap-space (after all what you seek is cache > speed).
On Wed, 2006-03-22 at 19:19 +0200, Tomas Simonaitis wrote:> I agree, 1-2GB of swap is good choice from my experience. > I don''t think you should run without swap at all - there usually is something > OS can push to swap and free some ram.Well it can''t hurt in the sense that it''s not like hard drive space is limited these days. Or unused swapping causing any harm. However if you start swapping more than 128MB or 256MB it''s more than likely going to be noticeable. More so for the intended application and goal. Thus it might be a good idea to have 512MB-1GB of swap. But as soon as you see >50MB or swap being used, or any noticeable use of swap. You will want to either get more ram, or make software adjustments. IMHO -- Sincerely, William L. Thomson Jr. Obsidian-Studios, Inc. http://www.obsidian-studios.com
wlagmay@yanbulink.net wrote:> > Hi All, > > This is out of the topic question, but I''m hoping that you can help me. If for > example I''m going to install a Fedora 4 64-bit with 8 to 12 Gig of physical > memory, how much swap file of directory do I need to create? >Many people on this thread are giving information which they believe to be true, but in most cases it isn''t (having the right mix of RAM/swap, and having data swapped to disk, can make your computer *more* responsive). If you want accurate information you should visit the kernel mailing list and/or read the kernel source / docs). There is a large amount of information available on how to tune your kernel swap variables. The same advice goes for squid (and how squid can best use RAM (eg: you *won''t* make squid perform better by assigning it large amounts of RAM directly). There is a large amount of posts on the squid-users mailing list regarding swap and memory use. HTH Brett