"Anne & Lynn Wheeler" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > > [EMAIL PROTECTED] (Martin Packer) writes: > > Note: Both the "25%" and the "1.5x" ROTs are trying to simplify > > probabilistic things (as always). So, you know in your shop what > > happens when you fail the ROT. In the former case paging performance > > tanks. In the latter it's a real bad news day when that 6GB DB2 > > subsystem dumps. (I've seen the latter happen and it's not pretty - > > when you don't have the paging space to contain it.) > > the idea behind "big pages" is similar to work on "log structured" > file systems ... collect enuf stuff together to do minimum number of > large writes and for those writes have to move the arm as little as > possible. "big pages" were original 10 4k pages that fit on a single > 3380 track. on page-out, ten pages from the virtual address space were > collected together and written to a single track ... the closest > available empty track in the direction of the arm motion (basically a > moving cursor algorithm that sweeped across the disk surface in > consistent direction). the theory was that the area just behind the > cursor would be full and the area just ahead of the cursor would be > nearly empty (requiring minimum arm motion to perform the write). >
Lynn, do you know from which statistics the 30% rule was deducted and to what extent it is still valid for current sizes of pageds, up to 4 GB? What I mean is, in a 625MB pageds you need a certain amount of free space to constantly provide space for "big pages": 70% = 425MB. If I have a 4GB pageds, do I need the same percentage (70%) of free space, or the same amount of free space (425MB) or something between 425MB and 2.8GB? Kees. ********************************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. ********************************************************************** ---------------------------------------------------------------------- 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
