Some time ago, I inquired on this list about direct I/O on Linux file systems. The idea was to specify direct I/O in init.ora parameter "filesystemio_options". To be able to do that, file system has to support direct I/O, in much the same way like Veritas quick I/O feature. The first candidate I investigated was SGI XFS, but my numerous attempts to get a definitive answer whether XFS supports it or not, the matter is still unresolved. It is my pleasure to report that the other candidate was much more open and provided a swift answer: JFS does support direct I/O. Here is the answer from Mr. Steve Best, principal IBM's developer of JFS for Linux.
Mladen Gogala wrote: > Hi Steve! > I apologize for contacting you directly, but I've been unable to > get an answer to my question any other way. The question is: > Does JFS on Linux support direct I/O, i.e. I/O that bypasses buffer > cache and behaves as if the file was a raw device. In other words, does > JFS on Linux has anything like Veritas Quick I/O?. Yes, the Linux kernel level has to be 2.4.15 or greater. On the 2.5.x kernel level direct I/O is there for JFS also. > Thanks in advance and I apologize once again for contacting you like > this. > -- > Mladen Gogala > Oracle DBA Thanks, Steve I will test the relative performance of JFS and ext3 file systems this weekend, on my own machine. My prediction is that JFS with direct I/O turned on will be much better then ext3 for updates and index scans, while ext3 will be faster for full table scans (prefetch). The plan is to download the latest version of the driver and link it into 2.4.22 kernel, then generate a table with approximately 1,000,000 records and test full table scans, index scans, serial updates, index updates, deletes and inserts. -- Mladen Gogala Oracle DBA Note: This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. Wang Trading LLC and any of its subsidiaries each reserve the right to monitor all e-mail communications through its networks. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorized to state them to be the views of any such entity. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
