On Sun, 29 May 2005, Greg Stark wrote:
> Oracle, Sybase, Postgres, other databases have hard requirements. They
> guarantee that when they acknowledge a transaction commit the data has been
> written to non-volatile media and will be recoverable even in the face of a
> routine power loss.
>
> They meet this requirement just fine on SCSI drives (where write caching
> generally ships disabled) and on any OS where fsync issues a cache flush. If
I don't know what facts "generally ships disabled" is based on, all of
the more recent SCSI drives (non SCA type though) I acquired came with
write cache enabled and some also with queue algorithm modifier set to 1.
> Worse, if the disk flushes the data to disk out of order it's quite
> likely the entire database will be corrupted on any simple power
> outage. I'm not clear whether that's the case for any common drives.
It's a matter of enforcing write order. In how far such ordering
constraints are propagated by file systems, VFS layer, down to the
hardware, is the grand question.
--
Matthias Andree
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
