Re: True ACID under linux (no fsync)? - Mailing list pgsql-general

From Marc SCHAEFER
Subject Re: True ACID under linux (no fsync)?
Date
Msg-id Pine.LNX.3.96.1001101111613.655A-100000@defian.alphanet.ch
Whole thread Raw
In response to True ACID under linux (no fsync)?  (Gary Howland (During daytime) <gary-daytime@hotlava.com>)
Responses Re: True ACID under linux (no fsync)?  (Bruce Guenter <bruceg@em.ca>)
List pgsql-general
On 31 Oct 2000, Gary Howland wrote:

> Just a quickie - I heard that linux does not have a working fsync() call

At least the manpage for fsync says that it does.

The implementation:

        /* .. finally sync the buffers to disk */
        dev = inode->i_dev;
        return sync_buffers(dev, 1);

It really looks like it IS implemented. But probably on Linux not just the
file data/metadata is synced, also all that device's data, which makes it
very inefficient, but presumably `safe'.

NB: don't forget that fsync() merely ensures that data was sent to the
disk controller. Maybe this one has a cache (e.g. a fast SCSI harddrive),
and if power fails, well. If fsync() was calling the SCSI FLUSH command,
maybe that could be done, but that would not just sync the file.




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