Swestore-dCache

Swestore is a robust, flexible and expandable short and medium term storage system aimed at storing large amounts of data produced by various Swedish research projects. It is based on the dCache software.

Swestore is distributed across the SNIC centres C3SE, HPC2N, Lunarc, NSC and Uppmax. Data is stored in two copies with each copy at a different SNIC centre. This enables the system to cope with a multitude of issues ranging from a simple crash of a storage element to losing an entire site while still providing access to the stored data.

One of the major advantages to the distributed nature of Swestore is the excellent aggregated transfer rates possible. This is achieved by bypassing a central node and having transfers going directly to/from the storage elements if the protocol allows it. Swestore can achieve aggregated transfer rates in excess of 100 Gigabit per second, but in practice this is limited by connectivity to the end user, each university or a limited number of files (typically max 1 Gbit/s per file/connection).

To protect against silent data corruption the dCache storage system checksums all stored data and periodically verifies the data using this checksum.

The dCache system does NOT yet provide protection against user errors like inadvertent file deletions and so on.

Getting access to Swestore

These steps are required for all PI:s and users of Swestore regardless of how the storage area later is accessed.

Apply for storage (for the PI)

All normal Swestore projects are managed using the SNIC User and Project Repository portal, SUPR. Please follow the instructions on the Apply for storage on Swestore page to apply for storage.

Acquire an eScience client certificate (for all users)

Swestore user authentication is currently done by user/client certificates. All project members needs to acquire a certificate by following the instructions on the Grid certificates page. This step can be performed while waiting for the storage application to be approved. If you already have a valid grid or eScience certificate you don't need to acquire another one.

Manage your eScience client certificate (for all users)

There are multiple suppliers of certificates. Depending on the supplier this step varies a bit.

For Digicert certificates

If intending to access Swestore from a SNIC resource, please make sure you also export the certificate, transfer it to the intended SNIC resource and prepare it for use with grid tools.

For Nordugrid certificates

Please make sure to also install your client certificate in your browser.

Register your eScience client certificate in SUPR (for all users)

All project members have to register in SUPR and be added to the approved project by the PI. All users also have to register their certificate in SUPR. This information is used by Swestore to authenticate the users when accessing the storage area. Registering the certificate is easy though. Make sure your certificate is stored in your browser, log in to SUPR , click "Personal Information" in the left menu, click "Register Client Certificate" and follow the instructions.

Using Swestore

Enabled access protocols

A design criteria for Swestore is to provide the storage over a number of standardized and public protocols. There is no vendor specific client needed for access.

GridFTP

Also called gsiftp. Well supported within Swestore.

Features: Transfer checksums. Writes goes directly to storage pools for high speed transfers.

Access URL: gsiftp://gsiftp.swestore.se/

HTTP/WebDAV

Contender for being the recommended protocol for Swestore.

Features: Direct support in web browsers. Redirected reads and writes if special url is used and client supports it.

Access URL: http://webdav.swestore.se/ (unauthenticated, read-only, non-redirected)

Access URL: https://webdav.swestore.se/ (authenticated, read-write, non-redirected)

Access URL: http://webdav.swestore.se:1080/ (unauthenticated, read-only, redirected)

Access URL: https://webdav.swestore.se:1443/ (authenticated, read-write, redirected)

NFSv4.1

Used by some communities, not recommended for general use

SRM - Storage Resource Manager

Used by some communities, not recommended for general use.

Access URL: srm://srm.swegrid.se/

Xrootd

Used by some communities, not recommended for general use

DCAP

Used by some communities, not recommended for general use

Download and upload data

Access using a web browser

Swestore is accessible in your web browser as a simple directory index interface at https://webdav.swestore.se/ To browse private data you need to have your certificate installed in your browser (default with Digicert certificates, see above). Projects are organized under the /snic directory as https://webdav.swestore.se/snic/YOUR_PROJECT_NAME/.

Access from the command line

There are several tools that are capable of using the protocols provided by Swestore. For interactive usage on SNIC clusters we recommend using the ARC tools which should be installed on all SNIC resources.

As an integration point for building scripts and automated systems we suggest using the curl program and library.

ARC

Please see the instructions for Accessing Swestore with the ARC client. Recommended method when logged in on SNIC resources.

lftp

See the instructions for Accessing Swestore with lftp.

cURL

Please see the instructions for Accessing Swestore with cURL. We suggest using this as integration point for building scripts and automated systems.

globus-url-copy

Please see the instructions for Accessing Swestore with globus-url-copy.

gfal2

(not documented yet)

Tools and scripts

There exists a number of tools and utilities developed externally that can be useful. Here are some links:

• ARC Graphical Clients - Contains the ARC Storage Explorer
• Transfer script, swetrans_arc, provided by Adam Peplinski / Philipp Schlatter
• Documentation of the ARC Python API (PDF)

Slides and more

Slides and material from seminar for Lund users on April 18th

Usage monitoring

• On the project page in SUPR: https://supr.snic.se
• On the monitoring server for Swestore: http://status.swestore.se/munin/monitor/monitor/ (only accessible from .se-domains.

Support

If you have any issues using Swestore, please do not hesitate to contact support@swestore.se.