Table of Contents
- Mounting Chimera through
- Communicating with Chimera
- Directory Tags
dCache is a distributed storage system, nevertheless it provides a single-rooted file system view. While dCache supports multiple namespace providers, Chimera is the recommended provider and is used by default.
The inner dCache components talk to the namespace via a module
PnfsManager, which in turn communicates with the
Chimera database using a thin Java layer, which in turn
communicates directly with the Chimera database. Chimera
allows direct access to the namespace by providing an
NFSv4.1 server. Clients can
NFS-mount the namespace locally.
This offers the opportunity to use OS-level tools like
ls, mkdir, mv for Chimera. Direct
I/O-operations like cp and cat are possible with
The properties of Chimera are defined in
customisation the files
/etc/dcache/dcache.conf should be
modified (see the section called “Defining domains and services”).
This example shows an extract of the
file in order to run dCache with
[namespaceDomain] [namespaceDomain/pnfsmanager] [namespaceDomain/nfs] nfs.version=3
If you want to run the
NFSv4.1 server you need to add the
nfs service to a domain in the
file and start this domain.
[namespaceDomain] [namespaceDomain/pnfsmanager] [namespaceDomain/nfs] nfs.version = 4.1
If you wish dCache to access your Chimera with a PostgreSQL user
other than chimera then you must specify the username and
Do not update configuration values in
since changes to this file will be overwritten by updates.