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Full Discussion: ZFS Filesystem
Operating Systems Solaris ZFS Filesystem Post 302953494 by achenle on Friday 28th of August 2015 02:19:09 PM
Old 08-28-2015
Quote:
Originally Posted by jlliagre
@achenle Yes, the ARC size should not be left unlimited when running an Oracle database. 1GB seems to be quite aggressive with a 32GB server though. That might waste memory and will likely affect overall performance.
Shouldn't impact performance at all. Database IO isn't going to go through the ARC - it'll be either direct IO or synchronous. Log files are generally streamed and forgotten about, so not having cached data from writes there isn't a big deal. And once the cache gets beyond a few tens of MB, the effective filesystem cache hit rate isn't going to change much anyway given the usage patterns on a pure DB server.

In my experience, performance often gets better because there's actually some free RAM on the server, so response to transient demands is a helluva lot faster.

If you want the DB to cache data, create a larger-than-default SGA for that, and create larger buffer and redo log pools in it as needed.

To get the max performance out of an Oracle DB running on Solaris, you really do have to get the ZFS ARC out of the way. (And you also have to be really careful about how your DB job processes behave - you do not want to have your DB trying to start or stop several thousand processes all at the same time...)

(I spent a few years consulting for a customer using multiple large Oracle RAC clusters on SPARC servers - one of my main jobs was getting the best possible performance out of the servers. Oracle on Solaris is as good as it gets for performance and reliability - yes, better than Linux for a lot of reasons - but there are some quirks - and the ARC is one of them.)
 

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Session::Store::Oracle(3)				User Contributed Perl Documentation				 Session::Store::Oracle(3)

NAME
Apache::Session::Store::Oracle - Store persistent data in a Oracle database SYNOPSIS
use Apache::Session::Store::Oracle; my $store = new Apache::Session::Store::Oracle; $store->insert($ref); $store->update($ref); $store->materialize($ref); $store->remove($ref); DESCRIPTION
Apache::Session::Store::Oracle fulfills the storage interface of Apache::Session. Session data is stored in a Oracle database. SCHEMA
To use this module, you will need at least these columns in a table called 'sessions': id varchar2(32) # or however long your session IDs are. a_session long To create this schema, you can execute this command using the sqlplus program: CREATE TABLE sessions ( id varchar2(32) not null primary key, a_session long ); If you use some other command, ensure that there is a unique index on the table's id column. CONFIGURATION
The module must know what datasource, username, and password to use when connecting to the database. These values can be set using the options hash (see Apache::Session documentation). The options are DataSource, UserName, and Password. Example: tie %hash, 'Apache::Session::Oracle', $id, { DataSource => 'dbi:Oracle:database', UserName => 'database_user', Password => 'K00l' }; Instead, you may pass in an already-opened DBI handle to your database. tie %hash, 'Apache::Session::Oracle', $id, { Handle => $dbh }; The last option is LongReadLen, which specifies the maximum size of the session object. If not supplied, the default maximum size is 8 KB. AUTHOR
This modules was written by Jeffrey William Baker <jwbaker@acm.org> A fix for the commit policy was contributed by Michael Schout <mschout@gkg.net> SEE ALSO
Apache::Session, Apache::Session::Store::DBI perl v5.12.1 2007-09-28 Session::Store::Oracle(3)
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