  The former CMS Run 2 High Level Trigger (HLT) farm is one of the largest
contributors to CMS compute resources, providing about 25k job slots for
offline computing. This CPU farm was initially employed as an opportunistic
resource, exploited during inter-fill periods, in the LHC Run 2. Since then, it
has become a nearly transparent extension of the CMS capacity at CERN, being
located on-site at the LHC interaction point 5 (P5), where the CMS detector is
installed. This resource has been configured to support the execution of
critical CMS tasks, such as prompt detector data reconstruction. It can
therefore be used in combination with the dedicated Tier 0 capacity at CERN, in
order to process and absorb peaks in the stream of data coming from the CMS
detector. The initial configuration for this resource, based on statically
configured VMs, provided the required level of functionality. However, regular
operations of this cluster revealed certain limitations compared to the
resource provisioning and use model employed in the case of WLCG sites. A new
configuration, based on a vacuum-like model, has been implemented for this
resource in order to solve the detected shortcomings. This paper reports about
this redeployment work on the permanent cloud for an enhanced support to CMS
offline computing, comparing the former and new models' respective
functionalities, along with the commissioning effort for the new setup.
