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RE: risk of data loss



You can mount a filesystem with a sync option of mount command. All writes to that filesystem will be reported to the applications as completed only after the data are written to the disk. The words 'written to the disk' means that the disk drive (or RAID controller) reported them to IDE/SCSI subsystem as written, however, at that moment the data may be actually residing in the cache of the disk drive/controller itself, not on the disk plates.

Alexey Fadyushin
Brainbench MVP for Linux
http://www.brainbench.com

> -----Original Message-----
> From: redhat-list-bounces redhat com [mailto:redhat-list-
> bounces redhat com] On Behalf Of oliver fenker bayerbbs com
> Sent: Thursday, August 31, 2006 12:13 PM
> To: redhat-list redhat com
> Subject: risk of data loss
> 
> Hello all,
> 
> I have to investigate under what circumstances a data loss in Linux might
> occur (e.g. server crash when data is in filesystem cache only). Data loss
> is possible if the application has got "I/O complete" although the data to
> be written is not yet "on disk". The handling within the storage
> (subsystem) is not in scope.
> 
> In addition I shall find out if there are special technologies used by
> some common Linux applications (Oracle, MySQL)  to circumvent this problem
> (e.g. Oracle with raw devices). Maybe there are certain options that
> minimize the risk of data loss (kernel options, special filesystems or
> filesystem options).
> 
> Can someone give me some advices or point me to some useful sites in the
> web, please? Any help is appreciated - thanx in advance.
> 
> Mit freundlichen Grüßen / Best Regards
> Oliver Fenker
> _________________________________________
> Bayer Business Services GmbH
> Oliver Fenker
> ITO-GDC-SEP-SSS
> Gebäude B 151, Raum 413
> 51368 Leverkusen
> 
> E-Mail: oliver fenker bayerbbs com
> Internet: www.bayerbbs.com
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