Re: Raw devices (Was:Re: NTFS, FAT32, etc.)

Alessandro Suardi (asuardi@uninetcom.it)
Fri, 09 May 1997 21:19:18 +0200

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.

Oracle7 writes *synchronously* changes made to data blocks in its
redo log files. When that is done, Oracle uses AIO (if you turned
the option on, of course ;) to write full database blocks on the
data files. If the system crashes between the two, Oracle will do
crash recovery reading from the redo logs.

Serious databases never trust the hardware :)

Ciao,

--alessandro <asuardi@uninetcom.it> <asuardi@it.oracle.com>

Linux-i386 kernel-2.1.36 libc-5.4.23 gcc-2.7.2.1 binutils-2.7.0.9