Monthly Archives: March 2007

Langeweile & andere Poel-Umbauten

Seit inzwischen 14 Monaten fährt der Passat und fährt und fährt. Nach dem Umbau auf PA Anfang 2006 gab es keinerlei Pölschäden, keine Ausfälle, kein Filterwechsel, nichts. Ob Raps oder Soja, Winter oder Sommer, das System scheint inzwischen ausgereift zu sein. Fast schon langweilig 🙂

Nach dem heutigen Ölwechsel steht nun eine Analyse des alten Motoröls an. In den vergangenen knapp 10.000 km wurden hierbei überwiegend Rapsraffinat aber auch 150 Liter Soja verfahren. Das Fahrprofil hierbei war zumeist Langstrecke auf der Autobahn aber auch einige kürzere Landstraßenetappen. Stadtverkehr – der sowieso nur einen sehr kleinen Anteil an der Gesamtfahrleistung hat – wurde mir Diesel bewältigt.

Andere Pöler waren dafür nicht ganz untätig. Folgende schöne Dokumentationen fielen mir hierbei insbesondere ins Auge:

High loads and low CPU usage? And now?

Recently one of our servers showed unusual high loads without any memory or CPU intensive tasks active. Some notes about how to debug io bottlenecks.

On Unix systems load is an inidcator for the number of processes active at a certain time. High loads mean that many processes are either processed by the CPU simulateniously or are waiting for input (network / io / …). The higher the load the more sluggish the system becomes.

In our case we had the situation that the system showed unusual high loads. Memory consumption was rather low; no swap space used whatsovever. The processlist (top) did not show any strange entries. No CPU or memory intensive processes were active.

With these observations, namely low memory, low cpu usage, the most promising point of attack seemed to be io performance. For this purpose – and as a sort of personal note as well – the following two commands proved quite handy:


vmstat 1 can be used to give you an overview over system, swap and io activity as well as memory consumption over time. In our case this proved that a lot of disk activity was going on.

iostat from the iostats package gives you a nice overview over disc activity and – even more important – the time your system is waiting for io activites to finish. With iowait well above 50 % the high system load could be explained.

Plone Upgrade and new Weblog

With the old Plone 2.1.x getting quite outdated an upgrade to the new Plone 2.5 version was iminent. While working on the site an upgrade to a new blogging software was also done.

Well, the plone upgrade from 2.1.1 to 2.5.2 went pretty smoothly. After backing up the complete site Python 2.4 and Zope 2.9.6 were installed from scratch. A new instance was created via mkzopeinstance and the old data.fs file as well as the products directory copied to this new installation.

But no "plone" folder anymore!

The only problem I encountered was that one folder named plone was no longer accessible. This stems from the changed internals of Plone 2.5. Here plone is a reserved view denoting a special view used from within Five. After some experiments I was able to change the name of the folder in an interactive session started by zopectl debug. Thats what I did:

# get the required privileges
admin = app.acl_users.getUserById(‘admin’)
admin = admin.__of__(app.acl_users)
from AccessControl.SecurityManagement import newSecurityManager
newSecurityManager(None, admin)

# create a dummy request
from Testing.makerequest import makerequest
app=makerequest(app)

# do the renaming
obj = app.<some.path>.plone
obj.aq_parent.manage_renameObject(o.getId(), ‘plone2’)

Quills as Blogging Solution

Also, since the old simpleblog based blogging solution is not compatible with Plone 2.5.x (and with Plone 2.1.x only through the ZMI) I played around with qSimpleBlog and Quills as products. With qSimpleBlog throwing errors about access to blogGlobals and other variables or templates left and right, Quills seems to be the way to go.