I'd expect I/O contention to force lower CPU usage...

Rather I'd look at the inparallel parameters or the use of
the spindle id number in the disklist (optional 4th field)
to force single threading at least on the server/client if
not on all clients.



> On Mon, Nov 24, 2003 at 10:48:43PM -0500, Eric Siegerman wrote:
> > On Sun, Nov 23, 2003 at 07:46:32PM -0500, Kurt Raschke wrote:
> > > ...when amdump runs, the load spikes to between 4.00 and
> > > 6.00, and the system becomes nearly unresponsive for the duration of
> > > the backup.  The server is backing up several local partitions, and
> > > also two partitions on remote servers.
> > 
> > Are you short of RAM?  If the system's paging heavily, that'd
> > make it crawl too.
> 
> No, the box has plenty of ram.
> 
>  
> > > I've tried starting amdump
> > > with nice and setting it to a low priority, but when gtar and gzip are
> > > started by amanda, the priority setting is somehow lost.
> > 
> > Not surprising.  Recall that Amanda runs client/server even when
> > backing up the server's DLE's.  The client-side processes are
> > descendents of [x]inetd, not of amdump, and so don't inherit the
> > latter's "nice" level.
> 
> I realized that about a second after I hit send.  However, the more
> that I look at it, I doubt that 'renice'ing tar and gzip will
> help--the box seems to have hard drive issues.  I suspect there may be
> a problem with the 3ware RAID card in there, or possibly the driver.
> 
>  
> > > The server
> > > isn't even trying to back up multiple partitions in parallel,
> > 
> > By this do you mean, "only one DLE at a time"; or "only one DLE
> > *from the server* at a time, along with remote backups in
> > parallel"?  If the latter, well, of course there's some amount of
> > server-side work even for the remote DLEs.  Is the compression
> > for the remote DLEs client- or server-side?  If the latter,
> > change "some amount" to "a lot" in the previous sentence :-)
> > 
> 
> Well, compression is client-side, and not every DLE is compressed, but
> as I recall from the runs the past few nights, the server is usually
> backing up one of the local DLEs as well one of the remote ones at the
> same time.  I suppose that if it's trying to store the incoming data
> from the remote client to the HD at the same time it's trying to back
> up a local DLE, that could cause contention for the disk array.  I'll
> try moving the holding disk to another drive (not part of the array on
> the 3ware card) and see if that improves things.
> 
> -Kurt