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SubjectRe: Raw devices (Was:Re: NTFS, FAT32, etc.)
On Thu, 8 May 1997, Martin von Loewis wrote:

> However, I thought that databases are interested in guaranteed completion,
> i.e. once write(2) returns, the system should guarantee that the data is
> really on disk. This is necessary for the transactional properties. Without
> such a guarantee, you can pretty much forget about transactional recoveries
> after a crash. Wouldn't O_SYNC give you the same properties? As for real
> implementations: Does anybody know whether the Adabas or Postgres Linux
> ports do use O_SYNC?

O_SYNC gives synchronous writes but using O_SYNC is not the same
as having raw devices. Raw device writes skip the buffer cache
but may or may not be completed before return depending whether
the kernel uses an intermediate buffer or not.

Mike

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