Identifying disk activity

Warren Block wblock at
Sun Aug 28 14:36:59 UTC 2011

On Sun, 28 Aug 2011, Polytropon wrote:

>>> Is there a way to force "synchronous disk activity"?
>> Turning off soft updates will help, but not make disk writes
>> totally synchronous.
> Can this be done easily (e. g. "tunefs -n disable <devices" in
> SUM to the unmounted partitions), without data loss? I have to
> admit that I've never tried that before.

SUM isn't needed, just have the filesystem unmounted.  Never had data 
loss from it.

Disabling write caching will also help to make filesystem writes more 
synchronous.  There are several sysctls and some information on soft 
updates at

More information about the freebsd-questions mailing list