Re: [Exadata] How do you use FlashDisk ?
Date: Sat, 19 Mar 2011 06:58:59 -0700 (PDT)
Message-ID: <235772.60751.qm_at_web113215.mail.gq1.yahoo.com>
Flash disks for WRITE operations are actually not that fast. I don't have the performance numbers here, but you really don't buy anything in terms of write performance with flash disks. So I would not recommend them for a disk group that will contain, say, online redo logs.
Also, with the Flash on Exadata keep in mind that it's a write through flash. Thus, the data cached in Flash is not based on what is written to the disks or read from them, but rather there is an algorithm that Oracle uses to determine what is put in flash and what is not. For example, large table scan blocks or large table loads are NOT going to to populate the flash cache, whereas frequently used blocks will. This makes the flash disks very much one of the key ingredients for the OLTP performance that we get on Exadata.
Cheers!
Robert G. Freeman
Master Principal Consultant, Oracle Corporation, Oracle ACE
Author of various books on RMAN, New Features and this shorter signature line.
Blog: http://robertgfreeman.blogspot.com
From: Surachart Opun <surachart_at_gmail.com> To: "Oracle-L_at_freelists.org" <oracle-l_at_freelists.org> Sent: Sat, March 19, 2011 2:34:48 AM
Subject: [Exadata] How do you use FlashDisk ?
On Exadata, You will have flashdisks. Idea to use them:
A. Make them for Exadata Smart Flashcache B. Use them for Grid Disk for ASM Disk Group, and store some database files. C. Use both A and B in Database System
I just curious, What should I concern, if use Flash Disks to be Grid Disks. What is you idea to use Flashdisk? However, Database System supports both OLTP and DSS.
Thank You
Surachart Opun
Oracle ACE, Contributor (Oracle User Group in Thailand)
skye: surachart_op
-- http://www.freelists.org/webpage/oracle-lReceived on Sat Mar 19 2011 - 08:58:59 CDT