From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Grzegorz Kulewski <kangur@polcom.net>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: How to flush data to disk reliably?
Date: Mon, 02 May 2005 18:52:38 +0100 [thread overview]
Message-ID: <1115056355.10370.37.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.62.0505021503470.11701@alpha.polcom.net>
> I am asking how to flush the data from these logs to disk. I know of
> several methods:
> 1. open with O_SYNC,
> 2. sync(2),
> 3. fsync,
> 4. fdatasync,
> 5. msync (if they are mmaped).
>
> Which of these are best and most reliable for (a/b) and for (IDE/SCSI)?
For scsi the combination of O_SYNC and ext3 or fsync and ext3 should be
reliable. fdatasync doesn't write back all the metadata so depending on
the use may not be sufficient. FAT based fs's I believe you need a
current kernel for full O_SYNC behaviour.
> What are differences between them?
See the manual pages and/or standard.
> other precautions that I should be aware of? What about write caches? Are
> write barriers implemented (on IDE and SATA/SCSI) or should I turn caches
> off?
SCSI shoule be fine, IDE turn off the write cache.
next prev parent reply other threads:[~2005-05-02 17:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-02 13:23 How to flush data to disk reliably? Grzegorz Kulewski
2005-05-02 17:52 ` Alan Cox [this message]
2005-05-02 19:18 ` Grzegorz Kulewski
2005-05-02 21:41 ` Alan Cox
2005-05-02 22:30 ` Bill Davidsen
2005-05-02 23:17 ` Arjan van de Ven
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