Skip to content

Latest commit

 

History

History
258 lines (178 loc) · 8.21 KB

dcache-minimal-installation.md

File metadata and controls

258 lines (178 loc) · 8.21 KB

The intent of this guide is to provide you with a minimal working dCache instance which you can explore. However, please note that there are many ways to configure dCache and your production instance will be more complex. The optimal choice depends on which hardware you wish to use and how dCache's users will interact with the system. There is no one size fits all.

Minimal dCache Installation Guide

Minimum System Requirements

  • Hardware:

    • Contemporary CPU
    • At least 1 GiB of RAM
    • At least 500 MiB free disk space

  • Software:

    • OpenJDK 11
    • Postgres SQL Server 13.0 or later
    • ZooKeeper version 3.5 (embedded)

Minimal Installation

Java

For this installation, we use OpenJDK 11 (java 17 for dCache version 10.2 and later)

sudo -s

yum install java-11-openjdk

dnf install java-11-openjdk-devel

For a production installation, you will need standalone ZooKeeper version 3.8 or later.

PostgreSQL

For this installation, we assume the database will run on the same machine as the dCache services that use it.

Start by installing PostgreSQL version 13.0 or later

dnf -y install postgresql-server

Initialise the database service, note that we do not start the database at this point, as we will make some tweaks to the configuration.

[root@neic-demo-1 centos]#  postgresql-setup --initdb
Initializing database in '/var/lib/pgsql/data'
Initialized, logs are in /var/lib/pgsql/initdb_postgresql.log

Make the database passwordless for this minimal installation. Inside the pg_hba.conf file in /var/lib/pgsql/data/pg_hba.conf comment out all lines except for

vi /var/lib/pgsql/data/pg_hba.conf
# TYPE  DATABASE    USER        IP-ADDRESS        IP-MASK           METHOD
local   all         all                                             trust
host    all         all         127.0.0.1/32                        trust
host    all         all         ::1/128                             trust

Then, start the database

systemctl enable --now postgresql

For a production installation, we recommend using the latest version and upgrading your PostgreSQL version as new versions become available. Remember to tune your PostgreSQL database for optimal performance depending on available hardware. Without doing this, you will see poor performance as PostgreSQL typically experiences low performance with its default configuration. In general, the database may be deployed on the same node as dCache or on some dedicated machine with db-specific hardware.

Creating PostgreSQL user and database

systemctl reload postgresql

dCache will manage the database schema by creating and updating the database tables, indexes etc. as necessary. However, dCache does not create the database.

Start by creating a user, we will call it dcache

createuser -U postgres --no-superuser --no-createrole --createdb --no-password dcache

Create the database using dcache to ensure correct database ownership. At this stage, we need only one database, chimera. This database holds dCache's namespace.

createdb -U dcache chimera

dCache

Four main components

All components in dCache are cells. They are independent and can interact with each other by sending messages just like microservices with message queues.

Door

User entry points (WebDav, NFS, FTP, DCAP, XROOT protocols)

PoolManager

The heart of a dCache System. When a user performs an action on a file, reading or writing, a transfer request is sent to the dCache system. Poolmanager then decides how to handle this request.

PNFSManager

Interface to a file system name space that maps dCache name space operations to file-system operations (Metadata DB, POSIX layer)

Pool

Service responsible for storing the contents of files. There must be always at least one pool. They talk all protocols.

In addition to the four main cells you need an access protocol and Zookeper for cell communication.

Zookeeper

A distributed directory and coordination service that dCache relies on.

Installation

dCache's current golden release is 10.2

rpm -ivh https://www.dcache.org/old/downloads/1.9/repo/10.2/dcache-10.2.19-1.noarch.rpm
Retrieving https://www.dcache.org/old/downloads/1.9/repo/9.2/dcache-9.2.19-1.noarch.rpm
warning: /var/tmp/rpm-tmp.gzWZPS: Header V4 RSA/SHA256 Signature, key ID 3321de4c: NOKEY
Verifying...                          ################################# [100%]
Preparing...                          ################################# [100%]
Updating / installing...
   1:dcache-9.2.19-1                  ################################# [100%]

Configuration files

There are three important configuration files:

/usr/share/dcache/defaults for default properties files
/etc/dcache/dcache.conf for main configuration file of dCache
/etc/dcache/layouts for properties/configuration updates

Configuration single process / one domain (simplest installation):

  • Shared JVM
  • Shared CPU
  • Shared log files
  • All components run the same dCache version
  • A process called DOMAIN?

Update dcache.conf by appending the following line

dcache.layout = mylayout

Create the mylayout.conf file inside the layouts directory and add the following contents

dcache.enable.space-reservation = false

[dCacheDomain]
 dcache.broker.scheme = none

[dCacheDomain/admin]
admin.paths.history=${host.name}/var/admin/history

[dCacheDomain/zookeeper]

[dCacheDomain/pnfsmanager]
 pnfsmanager.default-retention-policy = REPLICA
 pnfsmanager.default-access-latency = ONLINE

[dCacheDomain/poolmanager]

[dCacheDomain/gplazma]
gplazma.oidc.audience-targets=https://wlcg.cern.ch/jwt/v1/any
gplazma.oidc.provider!wlcg=https://wlcg.cloud.cnaf.infn.it/ -profile=wlcg -prefix=/ -suppress=audience

[dCacheDomain/webdav]
webdav.cell.name=WebDAV-${host.name}
#webdav.authn.basic = true
webdav.authn.protocol=http
webdav.authz.anonymous-operations=READONLY

Notes

  • In this installation, dCache will have only one domain, and it will not be connected to a tape system, hence, the values of retention-policy and access-latency are replica and online respectively. Additionally, dcache.broker.scheme = none tells dCache it is running stand-alone instance with no additional domains.
  • SpaceManager uses space reservation which is by default enabled, but for this minimal installation we change it to false.
  • Authorization is achieved by oidc plugin inside the gplazma component.
  • Our protocol, webdav, will allow share, migration, edit, copy, etc. of files.

We make use of a dCache script to create pool1 in /srv/dcache/pool-1 and dCache will add this pool to the pool service inside the dCache domain automatically.

dcache pool create /srv/dcache/pool-1 pool1 dCacheDomain
Created a pool in /srv/dcache/pool-1. The pool was added to dCacheDomain
in file:/etc/dcache/layouts/mylayout.conf.

Open mylayout.conf to verify pool1 was added.

[dCacheDomain/pool]
pool.name=pool1
pool.path=/srv/dcache/pool-1
pool.wait-for-files=${pool.path}/data

Start dCache

Using systemd service dCache creates a service for each defined domain in the mylayout.conf file. Before starting the service all dynamic systemd units should be generated.

systemctl restart dcache.target

To inspect all generated units in dcache.target

systemctl list-dependencies dcache.target

In our simple installation we have one domain hosting several services that look like this

systemctl list-dependencies dcache.target
|dcache.target
|● ├─dcache@dCacheDomain.service

Useful commands

Finally, we will leave you with some important commands to get you going.

systemctl status dcache@*
systemctl restart dcache.target 
systemctl stop dcache.target
journalctl -f -u dcache@dCacheDomain

Next steps

Now that you have learned how to install and start dCache, we encourage you to play around with the admin interface and run your own commands, add or split services into different domains, and work with diverse authentication methods and protocols. For a more in depth dCache installation, please refer to Chapter 2. Installing dCache.

Happy dCaching!