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Re: ext3 data=ordered - good enough for oracle?

Johann Lombardi wrote:
Given that the default journaling mode of ext3 (i.e. ordered), does not guarantee write ordering after a crash, is this journaling mode safe enough to use for a database such as Oracle? If so, how are out of sync writes delt with?

Oracle manages its own I/O cache in userspace and handles data coherency related
to that. So data=journal is useless in this case.
I guess databases such as Oracle uses O_SYNC to control the flushing of data or even O_DIRECT to bypass the kernel cache.

Thanks for the reply, Johann, but given that Oracle is still using the filesystem (unless you use raw devices or ASM), what good does caching do in case of a hard crash? The O_SYNC and O_DIRECT would help. Is there any way to verify that this is what Oracle actually does?

(Reason I'm asking is that I had a number of corruptions during the past year, and I have better things to do at nights than restoring databases.)

Kind regards,


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