Matty writes: > On 10/3/07, Roch - PAE <[EMAIL PROTECTED]> wrote: > > Rayson Ho writes: > > > > > 1) Modern DBMSs cache database pages in their own buffer pool because > > > it is less expensive than to access data from the OS. (IIRC, MySQL's > > > MyISAM is the only one that relies on the FS cache, but a lot of MySQL > > > sites use INNODB which has its own buffer pool) > > > > > > > The DB can and should cache data whether or not directio is used. > > It does, which leads to the core problem. Why do we have to store the > exact same data twice in memory (i.e., once in the ARC, and once in > the shared memory segment that Oracle uses)?
We do not retain 2 copies of the same data. If the DB cache is made large enough to consume most of memory, the ZFS copy will quickly be evicted to stage other I/Os on their way to the DB cache. What problem does that pose ? -r > > Thanks, > - Ryan > -- > UNIX Administrator > http://prefetch.net > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
