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ATLAS Vacuum VMs

To use the ATLAS Vacuum VMs, you need to agree with ATLAS what your Vac or Vcycle space's Panda queue name will be (usually ending in _VAC). You need to obtain a host certificate and key from your usual grid certificate authority which the VMs can use for authentication with ATLAS. You should normally use a DNS hostname which is specific to ATLAS but is part of your site's DNS space. It doesn't need to correspond to a real host or really exist as an entry on your DNS servers: just that you are entitled to register it. So if your site's domain name is then a certificate for with a DN like /C=CC/O=XYZ/ would be a good choice.

The hostcert.pem and hostkey.pem for this certificate should be placed in ATLAS's machinetype directory such as /var/lib/vac/machinetypes/atlas/ "atlas" in that file path can be replaced by another machinetype name if you prefer (eg atlasprod). This will be necessary if you wish to maintain more than one ATLAS machinetype in the same Vac or Vcycle space.

Vac/Vcycle configuration

A user_data template to contextualize CernVM for use with Vacuum Platform systems (Vac and Vcycle) is available at This should work with any recent version of Vcycle or with Vac 00.21 or later.

To use this template with Vac or Vcycle the following options should be included in the relevant [machinetype ...] section in the configuration.

accounting_fqan = /atlas/Role=NULL/Capability=NULL
backoff_seconds = 600
fizzle_seconds = 600
heartbeat_file = heartbeat
heartbeat_seconds = 600
machine_model = cernvm3
max_wallclock_seconds = 172800
root_image =
root_public_key = /root/.ssh/
user_data_file_hostcert = hostcert.pem
user_data_file_hostkey = hostkey.pem
user_data =
user_data_option_cvmfs_proxy = CHANGEME
user_data_option_queue = CHANGEME
target_share = CHANGEME
The CHANGEME values in the final options must be chosen to match your site's configuration:
  • user_data_option_cvmfs_proxy gives the URL(s) of the Squid proxy caches to be used by cvmfs within the VMs. For Vac-in-a-Box, the value must be
  • user_data_option_queue is the name of the PanDA resource. Typically this will be your GOCDB site name with a suffix like _VAC. For example, UKI-NORTHGRID-MAN-HEP_VAC
  • target_share Don't forget to set a target share for your new machinetype!

You may also wish to reduce max_wallclock_seconds but this must be done in line with the AGIS configuration used by the PanDA jobs that will run in your VMs. Mismatches will show up as "lost heartbeat" failures in PanDA jobs.

With Vac 00.21, it is not necessary to specify the amount of disk per-VM as Vac will share out the space in the vac_volume_group automatically. However, you should ensure there is at least 40GB per VM in the volume group.


The dashboard is extremely useful for monitoring the outcome of jobs. Go to the list of PanDA resources, find your Vac or Vcycle entry and look at the per-workernode and per-job listings to see what is going on. You can also look at similar PanDA resources at your site or using Vac etc elsewhere to see if problems are specific to you.