Content Distribution
This page is about the CVMFS service operated for EGI by RAL.
Overview
The CernVM-File System (CVMFS) provides a scalable, reliable and low-maintenance software distribution service. It was developed to assist High Energy Physics collaborations to deploy software on the worldwide distributed computing infrastructure used to run data processing applications. CVMFS is implemented as a POSIX read-only file system in user space. Files and directories are hosted on standard web servers and mounted in the universal namespace /cvmfs. CernVM-FS uses outgoing HTTP connections only, thereby it avoids most of the firewall issues of other network file systems. It transfers data and metadata on demand and verifies data integrity by cryptographic hashes. CVMFS is actively used by small and large collaborations. In many cases, it replaces package managers and shared software areas on cluster file systems as means to distribute the software used to process experiment data.
This documentation is for the VO content managers.
Official CVMFS pages
Requesting the creation of a new repository
In the case of a new repository for EGI, steps are described in PROC22.
Onboarding new Content Managers
Steps for a new VO Content Manager to be granted access to the Stratum-0.
Requesting access
Request access to the service sending an email to cvmfs-support@gridpp.rl.ac.uk In the email, include the following information:
- Name of the VO or CVMFS repository.
- Distinguish Name (DN) from your X509 grid certificate.
Mailing list
All VO content managers should join the CVMFS-UPLOADER-USERS mailing list in JISCMAIL.
Distributing new content
To login to the service, make sure you have a valid X509 proxy (with the same DN provided in this step), and execute the following command:
$ gsissh -p 1975 cvmfs-upload01.gridpp.rl.ac.uk
If you are the Content Manager for more than one repository, you would need to specify explicit which account you want to login to:
$ gsissh -p 1975 <myreposgm>@cvmfs-upload01.gridpp.rl.ac.uk
To copy data:
$ gsiscp -P 1975 <source> cvmfs-upload01.gridpp.rl.ac.uk:<destination>
After login, you will find a single directory in the home directory:
[myreposgm@cvmfs-uploader02 ~]$ ls
cvmfs_repo
Add to that directory the new content you want to distribute.
Files and directories cannot be distributed with CVMFS if they are not world-wide readable. You may want to ensure they have the right permissions with the following commands:
$ find . -type d -exec chmod go+rx {} \;
$ find . -type f -exec chmod go+r {} \;
Building your software
CVMFS is an infrastructure to distribute software world-wide. However, the uploader host should not be used for the purposes of building and compiling it prior to distribution.
The right approach is for you to have your own local building environment, and use the uploader host only to upload the new content for distribution.
If you have non-relocatable software, then you will need a /cvmfs/<myrepo>/
directory on your building host. One option is to use an actual CVMFS client, so
you have ready all the existing content being already distributed by CVMFS. By
default, the /cvmfs/ directory on a CVMFS client host is read-only, but that
can be solved using an
ephemeral writable container.