SquidFrontierSetupOld

These instructions are probably obsolete, but still useful.

• Go to SquidTier2 for pointers to the up-to-date instructions
• That page also has any attachments that are referenced below.
• -- RobertGardner - 18 May 2010

Squid Cache and FroNTier Client Setup

This page assumes that that you will be using Squid and connecting to the FroNTier server at the BNL Tier 1. To do this, you must do three things on Athena jobs using a local Squid cache on your site:

1. Install a Squid cache on your site.
2. Install the FroNTier client on your site (if running an Athena version < 15.4.0).
3. Modify the dblookup.xml file used by Athena jobs (if running an Athena version < 15.4.0).

In order to use Squid when running Athena locally, you use the FroNTier client with the Squid cache. Do not get confused! The FroNTier server software runs at BNL while Squid and the FroNTier client are run locally on your site. The FroNTier client should be installed in a directory that will appear in the path of Athena jobs running on your compute elements. Starting with release 15.4.0, setting up athena will setup the FroNTier client correctly and if your site only uses release 15.4.0 or higher you do not need to install the FroNTier client.

However John DeStefano [jd at bnl dot gov] is interested in knowing who is testing or using the FroNTier server and would appreciate it if you would let him know before you test. In addition, John maintains a Squid deployment table for Tier 2 sites that requires your updated site status:

• https://twiki.cern.ch/twiki/bin/view/Atlas/T2SquidDeployment#Deployment_Matrix

Squid Cache Installation

To install a Squid cache locally have your system manager follow the instructions at:

• https://www.racf.bnl.gov/docs/services/frontier/squid-installation

Two package formats are available for installation:

• Tarball: https://twiki.cern.ch/twiki/bin/view/CMS/SquidForCMS#Download_and_Install_Software
• RPM: https://twiki.cern.ch/twiki/bin/view/PDBService/SquidRPMsTier1andTier2

Setting $FRONTIER_SERVER (releases 15.4.0 and higher)

Starting with release 15.4.0, the use of the dblookup.xml is bypassed if the environmental variable $FRONTIER_SERVER is set. $FRONTIER_SERVER should be set to contain both the Squid proxyurl that is set to [your_proxy_server]:[port] and the FroNTier serverurl that is always set to (serverurl=http://squid-frontier.usatlas.bnl.gov:23128/frontieratbnl) in the US. One can also specify the compression level and failover servers $FRONTIER_SERVER also. Since the urls and modifiers are enclosed in parentheses the must be enclosed in quotes ("). An example using a Squid server at the MTW2 is:

export FRONTIER_SERVER="(proxyurl=http://10.255.2.11:3128)(serverurl=http://squid-frontier.usatlas.bnl.gov:23128/frontieratbnl)"

FroNTier Client Installation (NOT needed for Athena release 15.4.0 and higher)

Then FroNTier client provides both binaries (executable programs) and libraries and they should be installed in local directories that will appear in the path of Athena jobs running on your compute elements (i.e. the binaries should be in $PATH and the libraries should be in $LD_LIBRARY_PATH.

Download the latest client software (version 2.7.11 in this example) and install it as follows:

% cd /installation_dir/
% wget http://service-spi.web.cern.ch/service-spi/external/distribution/Frontier_Client_2.7.11__LCG_slc4_ia32_gcc34.tar.gz
% tar vxzf Frontier_Client_2.7.11__LCG_slc4_ia32_gcc34.tar.gz

Put the lib/ and bin/ directories of the FroNTier client into the appropriate paths:

% export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/install_dir/frontier_client/2.7.11/slc4_ia32_gcc34/lib"
% export PATH="$PATH:/install_dir/frontier_client/2.7.11/slc4_ia32_gcc34/bin"

These paths must be available to running jobs.

Modify dblookup.xml (NOT needed for Athena release 15.4.0 and higher)

Copy dblookup.xml from $CORAL_DBLOOKUP_PATH or $release/DBRelease/current/XMLConfig to a local directory, such as $my_DBLOOKUP_PATH.

Important Note: The dblookup.xml file is different for each ATLAS release. You must modify the file from the release that you are using!

Edit each <logical service> block in your local copy of dblookup.xml* to add the <service name /> element to connect to FroNTier and Squid, similar to the following:

<service name="frontier://BNL/(proxyurl=_[your_proxy_server]:[port]_)(serverurl=http://squid-frontier.usatlas.bnl.gov:23128/frontieratbnl)(retrieve-ziplevel=5)/ATLAS_COOLONL_INDET" accessMode="read" authentication="password" />

If you prefer to use environmental variables to set the proxyurl and the serverurl at run time, you can add the <service name /> element in this form:

<service name="frontier://BNL/(retrieve-ziplevel=5)/ATLAS_COOLONL_INDET" accessMode="read" authentication="password" />

and set $FRONTIER_PROXY1 and $FRONTIER_SERVER1 environmental variables:

export FRONTIER_PROXY1=[your_proxy_server]:[port]
export FRONTIER_SERVER1=http://squid-frontier.usatlas.bnl.gov:23128/frontieratbnl

To use your modified dblookup.xml file, override the original environment variable CORAL_DBLOOKUP_PATH to have your local directory containing the modified version of dblookup.xml first:

export CORAL_DBLOOKUP_PATH="$my_DBLOOKUP_PATH:$CORAL_DBLOOKUP_PATH"

Note: Starting with release 15, Athena looks in the run/ directory for dblookup.xml file regardless of the content of $CORAL_DBLOOKUP_PATH when running interactively but not for jobs submitted via pathena.

Note: 'retrieve-ziplevel' is best set to '5', but another setting ('0', etc.) may be optimal depending on your data access pattern.

Troubleshooting

To create a logfile of detailed debugging information, set these environment parameters:

 export FRONTIER_LOG_LEVEL=debug
 export FRONTIER_LOG_FILE=/tmp/frontier_client.log

Do not store the logging file on a networked filesystem, especially AFS, as this drastically slows down FroNTier/Squid. Check this log to verify whether any connections are succeeding.

-- FrederickLuehring - 12 Oct 2009
-- FrederickLuehring - 31 Jul 2009
-- RobertGardner - 04 Feb 2009
-- JohnDeStefano, DouglasSmith? - 09 Feb 2009
-- JohnDeStefano - 19 Feb 2009
-- JohnDeStefano, DaveDykstra? - 20 Feb 2009
-- JohnDeStefano - 20 Apr 2009
-- JohnDeStefano - 05 May 2009