More IO identification problems

Adam Vande More amvandemore at
Fri Nov 26 19:14:48 UTC 2010

On Fri, Nov 26, 2010 at 8:33 AM, jhell <jhell at> wrote:

> > Perhaps it's some external component?
> > E.g. hald is known to perform some disk/media checks every two seconds.
> >
> As well syslod will also cause sync to happen prematurely when something
> goes to log.
> syslog.conf(5):
> ***
>  To ensure that kernel messages are written to disk promptly,
> syslog.conf calls fsync(2) after writing messages from the kernel.
> Other messages are not synced explicitly. You may prefix a pathname
> with the minus sign, ``-'', to forego syncing the specified file
> after every kernel message. Note that you might lose information if
> the system crashes immediately following a write attempt. Neverthe-
> less, using the ``-'' option may improve performance, especially if
> the kernel is logging many messages.
> ***
> This is obviously the old way of ensuring logs are written to disk
> before crash but now ZFS is handled differently. Check to see if adding
> '-' to your syslog entries relieves that problem as ZFS will do the
> right thing to ensure your data is written to disk.

 Thanks, avg and jhell.  hald was indeed the culprit, and a
"hal-disable-polling --device /dev/cd0" has restored my sanity.  I never
liked the cd notifications anyway.

Adam Vande More

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