Installing the StashCache Origin¶
This document describes how to install a StashCache origin service. This service allows an organization to export its data to the StashCache data federation.
The origin must be registered with the OSG prior to joining the data federation. You may start the registration process prior to finishing the installation by using this link along with information like:
- Resource name and hostname
- VO associated with this origin server (which will be used to determine the origin's namespace prefix)
- Administrative and security contact(s)
- Who (or what) will be allowed to access the VO's data
- Which caches will be allowed to cache the VO data
Before starting the installation process, consider the following points:
- Operating system: A RHEL 7 or compatible operating system.
- User IDs: If they do not exist already, the installation will create the Linux user IDs
xrootd; only the
xrootduser is utilized for the running daemons.
- Host certificate: The origin service uses a host certificate to authenticate with the caches it serves. The host certificate documentation provides more information on setting up host certificates.
- Network ports: The origin service requires the following ports open:
- Inbound TCP port 1094 for file access via the XRootD protocol
- Outbound TCP port 1213 to
redirector.osgstorage.orgfor connecting to the data federation
- Outbound UDP port 9930 for reporting to
- Hardware requirements: We recommend that an origin has at least 1Gbps connectivity and 8GB of RAM. We suggest that several gigabytes of local disk space be available for log files, although some logging verbosity can be reduced.
As with all OSG software installations, there are some one-time steps to prepare in advance:
Installing the Origin¶
The origin service consists of one or more XRootD daemons and their dependencies for the authentication infrastructure. To simplify installation, OSG provides convenience RPMs that install all required software with a single command:
[email protected] # yum install stash-origin
For this installation guide, we assume that the data to be exported to the federation is mounted at
and owned by the
Configuring the Origin Server¶
stash-origin package provides a default configuration files in
Administrators may provide additional configuration by placing files in
of the form
/etc/xrootd/config.d/1*.cfg (for directives that need to be processed BEFORE the OSG configuration)
/etc/xrootd/config.d/9*.cfg (for directives that are processed AFTER the OSG configuration).
You must configure every variable in
The mandatory variables to configure are:
||The mounted filesystem path to export; this document calls it
||The resource name registered with OSG|
||The directory relative to
For example, if the HCC VO would like to set up an origin server exporting from the mount point
and HCC's registered namespace is
/hcc, then the following would be set in
set rootdir = /mnt/stash set resourcename = HCC_STASH_ORIGIN
And the following would be set in
set originexport = /hcc
With this configuration, the data under
/mnt/stash/hcc/bio/datasets would be available under the StashCache path
/hcc/bio/datasets and the data under
/mnt/stash/hcc/hep/generators would be available under the StashCache path
If you want to run origins for authenticated and unauthenticated data, you must run them on separate hosts. This requires registering a resource for each host. This requirement will be removed in a future version of StashCache.
The StashCache namespace is global within a data federation. Directories you export must not collide with directories provided by other origin servers; this is why the explicit registration is required.
Manually Setting the FQDN (optional)¶
The FQDN of the origin server that you registered in Topology may be different than its internal hostname
(as reported by
For example, this may be the case if your origin is behind a load balancer such as LVS or MetalLB.
In this case, you must manually tell the origin services which FQDN to use for topology lookups.
- Create the file
/etc/systemd/system/stash-origin-authfile.service.d/override.confwith the following contents:
[Service] Environment=ORIGIN_FQDN=<Topology-registered FQDN>
Managing the Origin Service¶
The origin service consists of the following SystemD units that you must directly manage:
||Performs data transfers (unauthenticated instance)|
||Performs data transfers (authenticated instance)|
These services must be managed with
systemctl and may start additional services as dependencies.
As a reminder, here are common service commands (all run as
|To...||On EL7, run the command...|
|Start a service||
|Stop a service||
|Enable a service to start on boot||
|Disable a service from starting on boot||
In addition, the origin service automatically uses the following SystemD units:
||Integrates the origin into the data federation (unauthenticated instance)|
||Integrates the origin into the data federation (authenticated instance)|
||Updates the authorization files periodically|
Verifying the Origin Server¶
Once your server has been registered with the OSG and started, perform the following steps to verify that it is functional.
To verify that your origin is correctly advertising its availability, run the following command from the origin server:
[[email protected] ~]$ xrdmapc -r --list s redirector.osgstorage.org:1094 0**** redirector.osgstorage.org:1094 Srv ceph-gridftp1.grid.uchicago.edu:1094 Srv stashcache.fnal.gov:1094 Srv stash.osgconnect.net:1094 Srv origin.ligo.caltech.edu:1094 Srv csiu.grid.iu.edu:1094
The output should list the hostname of your origin server.
Testing directory export¶
To verify that the directories you are exporting are visible from the redirector, run the following command from the origin server:
[[email protected] ~]$ xrdmapc -r --verify --list s redirector.osgstorage.org:1094 <EXPORTED DIR> 0*rv* redirector.osgstorage.org:1094 >+ Srv ceph-gridftp1.grid.uchicago.edu:1094 ? Srv stashcache.fnal.gov:1094 [not authorized] >+ Srv stash.osgconnect.net:1094 - Srv origin.ligo.caltech.edu:1094 ? Srv csiu.grid.iu.edu:1094 [connect error]
<EXPORTED_DIR> for the directory the service is suppose to export.
Your server should be marked with a
>+ to indicate that it contains the given path and the path was accessible.
Testing file access¶
To verify that you can download a file from the origin server, use the
<TEST FILE> in
<EXPORTED DIR>. Where
<TEST FILE> can be any file. The
stashcp tool is available in the
Run the following command:
[[email protected]]$ stashcp <TEST FILE> /tmp/testfile
If successful, there should be a file at
/tmp/testfile with the contents of the test file on your origin server.
If unsuccessful, you can pass the
-d flag to
stashcp for debug info.
You can also test directly downloading from the origin via
xrdcp, which is available in the
Run the following command:
[[email protected]]$ xrdcp xroot://<origin server>:1094/<TEST FILE> /tmp/testfile
Registering the Origin¶
To be part of the OSG StashCache Federation, your origin must be
registered with the OSG. The service type is
XRootD origin server.
The resource must also specify which VOs it will serve data from.
To do this, add an
AllowedVOs list, with each line specifying a VO whose StashCache data the resource is willing to host.
MY_STASHCACHE_ORIGIN: Service: XRootD origin server Description: StashCache origin server AllowedVOs: - GLOW - OSG
You can use the special value
ANY to indicate that the origin will serve data from any VO that puts data on it.
In addition to the origin allowing a VOs via the
that VO must also allow the origin in its
See the page on getting your VO's data into StashCache.