Re: Raw Partitions and File Systems - Same Instance, OPS
Date: 1995/12/27
Message-ID: <4bqj34$or2_at_inet-nntp-gw-1.us.oracle.com>#1/1
rellison_at_nosc.mil (Richard Ellison) writes:
>I have been investigating creating raw partitions on our Sequent in addition
>to the existing file systems for the following reasons:
>* Improved I/O performance
>* Able to span physical drives thereby getting larger than our 2 GB max file
>system. This is needed to store the large volume of archive redo logs we
>generate.
>* Have our system administrator learn how to manage raw partitions. (Maybe
>archive redos is not the best place to learn raw partitions...)
>* Gain knowledge prior to potentially implementing Oracle Parallel Server.
>Anyway...
>* Can this mix of raw partitions and file systems be done?
Yes, Oracle does not distinguish between UNIX file systems and raw devices.
It sees a big chunk of memory and uses it as such. They can co-exist.
>* Are raw partitions really worth the headache?
Yes and No. yes if you want mission critical performance and you want
some quick responses to queries and if you want to use parallel server option.
No if you think managing raw devices is a headache. Raw devices reduces
your backup option to dd. cpio and tar won't work. Typically raw devices
are recommended in a RAID environment where the redundancy makes the chances
of losing data slim. Needless to say, a good, tested backup strategy is
crucial even in this environment. A good UNIX system admin is a prerequisite
for running a database in raw devices.
>* Do you absolutely have to have raw paritions in order to run Oracle Parallel
>Server?
Absolutely YES. Oracle parallel server is a set of database files mounted
by multiple instances. Concurrency is manged by a vendor provided lock
manager. The conventional UNIX file system does not allow this and hence the
need to use raw devices. In fact, a prerequiste for installing the parallel
server option is to have the lock manager running. Contact your hardware/O/S
vendors for more details.
Refer to the Oracle Server for UNIX administrator's guide. This has the answer
to all of the above. Also check out the paper by Cary Millsap on
"The decision to use raw devices"
>Thanks...
You are welcome.
>Rick Ellison
>DBA
Mahesh Vallampati
Oracle Services
Houston, TX-77002
mvallamp_at_us.oracle.com
713-750-5002
Received on Wed Dec 27 1995 - 00:00:00 CET