Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.media.kyoto-u.ac.jp!postnews.google.com!i39g2000cwa.googlegroups.com!not-for-mail From: "Joel Garry" Newsgroups: comp.databases.oracle.server Subject: Re: sga_max_size - pre-allocated at instance startup? Date: 3 Mar 2006 15:26:40 -0800 Organization: http://groups.google.com Lines: 35 Message-ID: <1141428400.750341.129830@i39g2000cwa.googlegroups.com> References: <1141321044.417391.133330@z34g2000cwc.googlegroups.com> <1141373722.984104@proxy.dienste.wien.at> NNTP-Posting-Host: 67.112.255.226 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1141428405 32620 127.0.0.1 (3 Mar 2006 23:26:45 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 3 Mar 2006 23:26:45 +0000 (UTC) In-Reply-To: <1141373722.984104@proxy.dienste.wien.at> User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0),gzip(gfe),gzip(gfe) X-HTTP-Via: 1.0 ISA-OC2 Complaints-To: groups-abuse@google.com Injection-Info: i39g2000cwa.googlegroups.com; posting-host=67.112.255.226; posting-account=YRNZ5wwAAAAg-yYjMFwy3FyWUbPiwNdq Xref: dp-news.maxwell.syr.edu comp.databases.oracle.server:262757 Laurenz Albe wrote: >We asked specifically for AIX and the answer was: yes, all the shared >memory in SGA_MAX_SIZE is allocated at instance startup, but only >SGA_TARGET of it is actually used. AIX is weird, see metalink on lock_sga and what _it_ requires, and it varies by version of everything. Mladen Gogala wrote: >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. On hp-ux, I see it all being allocated on startup, even if startup screws up, sometimes leaving shared memory associated with a non-extant process, and not removable with ipcrm -m. Only reason I had to reboot with 6 month uptime (some processes were unable to get sockets). Solaris and hp-ux have always implemented shared memory different from each other in my experience (back to SunOS 1.2 and hp-ux 9). Just because Posix has a service definition and ipc* have the same syntax doesn't mean things work the same, although they are getting closer in more recent Oracle. Hey, I remember when posix was added to VMS and the joke was "VMS is more unix than unix." jg -- @home.com is bogus. http://groups.google.com/group/comp.sys.dec/browse_thread/thread/1682d35ab49975bc/8fef0722a61171e8?lnk=st&q=%22vms+is+more+unix+than+unix%22&rnum=1&hl=en#8fef0722a61171e8