softupdates and two different MTAs

[Claus Assmann]

On Fri, Mar 19, 2004, Dan Nelson wrote:
> In the last episode (Mar 16), Claus Assmann said:
> > | program       | FS               |  writes | reads |
> > |---------------+------------------+---------+-------|
> > | sm8.12.11     | UFS, softupdates |     236 |     0 |

> > | sm9.0.0.12    | UFS, softupdates |    3500 |     4 |

> So something is either not fsyncing, or there is clustering going on
> behind the scenes.  The sm8 softupdates count is disturbingly low, even
> assuming good clustering.

You are right, it is too low. After following your advice about
adding the disk I/O stats to sendmail 8 itself, I finally found
that the cf file had SuperSafe=m, which causes it to not issue most
of the fsync(2) calls. With SuperSafe=true sm8 uses about twice as
many disk writes as sm9 and hence the latter is about two times
faster than the former.

Thanks for your reply!