Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: Should raw I/O be added to the kernel? | Date | 22 Jan 1999 02:19:17 GMT |
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Followup to: <199901211735.RAA04836@dax.scot.redhat.com> By author: "Stephen C. Tweedie" <sct@redhat.com> In newsgroup: linux.dev.kernel > > Yes you can. The way these applications work is to write all of the > data for a commit, and to wait for it to complete before finally writing > a commit record. That way, provided the OS does not acknowledge the > write before it actually reaches the disk, the application can guarantee > enough about the write ordering to be sure about data consistency. Raw > IO, O_SYNC and fsync() provide enough support for the application to get > this right, but fsync() does not provide guaranteed IO error > notification so is not sufficient in the presence of errors. >
Actually, it is better than that: as long as the commit record cannot pass the data records, you can roll back to a consistent state.
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