On Thu, 7 Aug 2008 17:02:36 -0500, Rick Fochtman wrote: > >I typically give 1/3 of a 3390-3 volume for a single paging dataset, >populating the remainder of the volume with low-use datasets.
That's about 1 GB per page DS. If you have ten of them that's only 10 GB of local paging space. I think that's pretty small today. And then you'd need another 10 to 20 GB of "low use" data sets to come close to filling the packs. Non-managed data sets, at that. I'd go with full pack data sets on mod-3 volumes or about 4GB data sets on larger volumes. >I also >plan on being ready to add at least two more page datasets of similar >size, in case of an emergency that might arise due to shortages. Yes, you might as well keep all your page data sets the same size, including spares, if you keep them. Set PAGTOTL to 255. The cost is very small. IIRC, 96 bytes of ESQA for the PARTE for each page data set that is not actually used. The cost of not being able to add another may be an IPL. Then again, if you are keeping page data sets around to add in case you need them, why not just add them? > >Running roughly 300 address spaces, I found that four of these page >datasets was about right, with no more than 50% utilization of any one >of them. IIRC, four is not considered a sufficiently robust paging subsystem to deal with spikes that occur when taking SVCDUMPs. A minimum of six is recommended. And 50% is too high. IIRC, beyond about 30% it becomes more difficult for ASM to find contiguous free pages for efficient page out operations. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
