Swap Size for Solaris/IDS
Folks, This topic is a mixture of Unix and Informix sysadmin. I posted here because I'm interested specifically (and only) in an Informix context. The questions are: Should swap partition be > 0? If so, how does one determine size? I have started some research in the newsgroups, as well as SunWorld, and Cockroft material. I have a long way to go. I'm finding the topic confusing, with seemingly contradictory recommendations ranging from "swap should be 3 times memory" to "don't need swap if you have more than several 100 MB memory". Background: We are using IDS 7.3 (likely soon to be 64-bit 7.30.FC7A-1) on Solaris 2.6 (definitely soon to be Solaris 7) on Sun UltraEnterprise 3000 with 3 CPUs, 2.5 GB memory, and 15 drives (distributed 3/6/6) on 3 controllers. The system is used exclusively for DSS (data warehouse). There is only a single IDS instance. At the moment, the warehouse is embryonic, being <1 GB. We expect it to be at least a year before size doubles, thus for near term, it is feasible to max out buffers (512K @ 2K each = 1 GB mem for buffers) and make everything resident. This still leaves decent amount DSS memory, say 1 GB, for various pools (sorts, etc.). I would like to know how to size swap for the upcoming Solaris 7 install. It would seem right off the bat that, if we do have swap, we certainly can't even have 1X amount of memory, since 2.5GB is already greater than the max allowed Solaris swap size of 2GB. What are the implications of swap being < RAM? It would seem to me that swap space becomes less significant as the ratio of swap to memory decreases. Of course, that can't be completely correct, if the advocates of small swap spaces are valid. Bottom line question: What size should I make swap, and what factors determine it? Thank you for any thoughts or comments. Regards, David Grove
In article <37fbcc83@news.gci.net>, David Grove <david_grove@health.stat e.ak.us> writes >Folks, > >This topic is a mixture of Unix and Informix sysadmin. I posted here >because I'm interested specifically (and only) in an Informix context. > >The questions are: Should swap partition be > 0? If so, how does one >determine size? > >I have started some research in the newsgroups, as well as SunWorld, and >Cockroft material. I have a long way to go. I'm finding the topic >confusing, with seemingly contradictory recommendations ranging from "swap >should be 3 times memory" to "don't need swap if you have more than several >100 MB memory". > >Background: We are using IDS 7.3 (likely soon to be 64-bit 7.30.FC7A-1) on >Solaris 2.6 (definitely soon to be Solaris 7) on Sun UltraEnterprise 3000 >with 3 CPUs, 2.5 GB memory, and 15 drives (distributed 3/6/6) on 3 >controllers. The system is used exclusively for DSS (data warehouse). >There is only a single IDS instance. At the moment, the warehouse is >embryonic, being <1 GB. We expect it to be at least a year before size >doubles, thus for near term, it is feasible to max out buffers (512K @ 2K >each = 1 GB mem for buffers) and make everything resident. This still >leaves decent amount DSS memory, say 1 GB, for various pools (sorts, etc.). > >I would like to know how to size swap for the upcoming Solaris 7 install. > >It would seem right off the bat that, if we do have swap, we certainly can't >even have 1X amount of memory, since 2.5GB is already greater than the max >allowed Solaris swap size of 2GB. What are the implications of swap being < 2Gb per swap device. But you can have more than one swap device.. >RAM? It would seem to me that swap space becomes less significant as the >ratio of swap to memory decreases. Of course, that can't be completely >correct, if the advocates of small swap spaces are valid. > >Bottom line question: What size should I make swap, and what factors >determine it? > >Thank you for any thoughts or comments. > >Regards, > >David Grove > > -- David Williams