Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newscon02.news.prodigy.com!prodigy.net!newsmst01b.news.prodigy.com!prodigy.com!postmaster.news.prodigy.com!newssvr24.news.prodigy.net.POSTED!a25fe021!not-for-mail From: Mladen Gogala Subject: Re: sga_max_size - pre-allocated at instance startup? User-Agent: Pan/0.14.2.91 (As She Crawled Across the Table) Message-Id: Newsgroups: comp.databases.oracle.server References: <1141321044.417391.133330@z34g2000cwc.googlegroups.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Lines: 43 NNTP-Posting-Host: 69.177.91.154 X-Complaints-To: abuse@prodigy.net X-Trace: newssvr24.news.prodigy.net 1141394029 ST000 69.177.91.154 (Fri, 03 Mar 2006 08:53:49 EST) NNTP-Posting-Date: Fri, 03 Mar 2006 08:53:49 EST Organization: SBC http://yahoo.sbc.com X-UserInfo1: SCSYQN_@OXWMRULYBJKD]_\@VR]^@B@MCPWZKB]MPXHZUSAANVUEAE[YETZPIWWI[FCIZA^NBFXZ_D[BFNTCNVPDTNTKHWXKB@X^B_OCJLPZ@ET_O[G\XSG@E\G[ZKVLBL^CJINM@I_KVIOR\T_M_AW_M[_BWU_HFA_]@A_A^SGFAUDE_DFTMQPFWVW[QPJN Date: Fri, 03 Mar 2006 13:53:49 GMT Xref: dp-news.maxwell.syr.edu comp.databases.oracle.server:262689 On Thu, 02 Mar 2006 09:37:24 -0800, deebeeay@gmail.com wrote: > Hi Guys, > > Is sga_max_size pre-allocated in memory at instance startup? Let's check: SQL> show parameter sga NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ lock_sga boolean FALSE pre_page_sga boolean FALSE sga_max_size big integer 320M sga_target big integer 256M SQL> [root@medo ~]# ipcs -m|grep oracle;bc 0xa582a75c 589838 oracle 640 339738624 23 bc 1.06 Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty'. 339738624/1048576 324 $ uname -a Linux medo.noip.com 2.6.15.4 #1 Tue Feb 21 20:34:25 EST 2006 i686 athlon i386 GNU/Linux $ As oracle uses the same POSIX IPC services across the whole range of Unix-like platforms, one can safely conclude that oracle will allocate all of the shared memory specified in the SGA_MAX_SIZE at the instance startup. > > I can't seem to find a definitive answer from docs or the web. Some > suggest yes but only on certain OSs. The definitive anser is "maybe". -- http://www.mgogala.com