CP doesn't have a problem with "some" movement between the 2 GB line, it's when you start pounding the I/O.
If you have multiple Oracle images, you need to look at it as the sum of the SGAs. Only 2GB of that can be below the line, obviously. And if the images are doing a lot of I/O, that part above the line has to be swapped below the line for the I/O. You start thrashing. Then, you also have to add in the other machines that may be doing I/O. That all has to be below the line. It seems to me that DB2 does this better then Oracle. It seems that the SGA contains many things, includeing buffers and cache. Cache can be above the line. When active, buffers have to be below the line. But it doesn't seem to me, but I haven't looked closely, that the SGA is a mixture of everything and not divided up into specified address ranges. That seems to mean that all of SGA can be used for I/O. In DB2, there is buffers and there is cache. Two different storage pools. The buffers should stay below the line, for I/O, but the cache can float above the line. But the 64 bit CP will eliminate the 2GB line, so it will become a moot point. Tom Duerbusch THD Consulting >>> [EMAIL PROTECTED] 03/01/05 10:19 AM >>> We've gotten our SGA up to about 1.5G. We run it in a 64-bit guest to give a little extra "room". So far we haven't had any issues moving pages across the bar. -----Original Message----- From: Tom Duerbusch [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 01, 2005 10:15 AM To: [email protected] Subject: Re: Using more than 2GB in a SuSE 8 31 bits Also, Oracle 9 has a SGA limit of about 750MBs. There are some tricks to get it up to around 900 MBs. With that restriction, it is difficult to get Oracle to actually need the full 2GB that 31 bit addressing can give. But if you do go to Oracle 10g, don't think you can give it a lot of storage w� operating under z/VM 5.1. CP is still 31 bit and all I/O has to go on below the 2 GB line. Giving very large SGA, because you can, will result in lower performance and high CPU rates as the SGA is constently shuffled above and below the 2GB line. The 64 bit CP is comming soon. Until then, if you do have the requirement to use large SGAs, then you have to run directly on LPAR for that z/Linux machine. Tom Duerbusch THD Consulting >>> [EMAIL PROTECTED] 03/01/05 9:53 AM >>> SuSE 8 31 bit Linux can only address 2 gigabytes of real memory. So not only do you more than likely need oracle 10G, you need SuSE 8.x 64 bit Linux to be able to give oracle 10G more than 2 gigs of real in the first place. "Little, Chris" <[EMAIL PROTECTED] hs.org> To Sent by: Linux on [email protected] 390 Port cc <[EMAIL PROTECTED] IST.EDU> Subject Re: Using more than 2GB in a Suse 8 31 bits 03/01/2005 09:31 AM Please respond to Linux on 390 Port <[EMAIL PROTECTED] IST.EDU> 9i can run in a 64 bit guest, but can only address 2 gig. That is useful if you need a really large SGA. If you need more, then you'll want to run 10g, which _is_ 64 bit. -----Original Message----- From: Saulo Augusto Silva [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 01, 2005 9:30 AM To: [email protected] Subject: Using more than 2GB in a Suse 8 31 bits Hi all , This is the first message that I am writing to this list . So my question is : How can I use more than 2 GB of RAM to a linuxGuest in a zVM 4.4 . We are making some teste with Oracle 9i and the system only recognize 2 GB of memory . Any one can help ? -- Saulo Augusto Silva ----------------------------- Analista de Suporte Engenheiro Certificado RedHat Linux Profissional Certificado LPIC-I [EMAIL PROTECTED] [EMAIL PROTECTED] 71 3115 7677 "As informaC'C5es existentes nesta mensagem e nos arquivos anexados sC#o para uso restrito, com sigilo protegido por lei. Caso nC#o seja o destinatC!rio, favor apagar esta mensagem e notificar o remetente. 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