RE: Bigfile tablespaces on OS filesystems?
From: Allen, Brandon <Brandon.Allen_at_OneNeck.com>
Date: Mon, 21 Sep 2009 11:12:08 -0700
Message-ID: <64BAF54438380142A0BF94A23224A31E112B688517_at_ONEWS06.oneneck.corp>
No, the entire 500GB won't have to be read every time the file is accessed - the OS will do block-level IO just like ASM. The main difference is just that the I/O will be buffered by the OS (unless you have filesystem with an option for direct IO) so it might add a few microseconds to every I/O for the extra memory-to-memory copy, and will waste some of your RAM for holding this extra copy in the OS buffer in addition to Oracle's buffer. The file size doesn't affect r/w performance - the number of disks, speed of disks, SAN cache, fibre channels, etc. are what will affect the performance. I believe asynch IO on HPUX is simulated with multiple Oracle DB writers so you might want to look into that.
Date: Mon, 21 Sep 2009 11:12:08 -0700
Message-ID: <64BAF54438380142A0BF94A23224A31E112B688517_at_ONEWS06.oneneck.corp>
No, the entire 500GB won't have to be read every time the file is accessed - the OS will do block-level IO just like ASM. The main difference is just that the I/O will be buffered by the OS (unless you have filesystem with an option for direct IO) so it might add a few microseconds to every I/O for the extra memory-to-memory copy, and will waste some of your RAM for holding this extra copy in the OS buffer in addition to Oracle's buffer. The file size doesn't affect r/w performance - the number of disks, speed of disks, SAN cache, fibre channels, etc. are what will affect the performance. I believe asynch IO on HPUX is simulated with multiple Oracle DB writers so you might want to look into that.
Regards,
Brandon
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