The In2p3/BaBar xrootd system

In2p3 provides data access primarily for BaBar analysis users. Here is a schematic of the system:


(Note: all of this is an Internet Free Zone (IFZ) and hence not visible to the outside world.)

The redirector(s)

In2p3 currently uses a single redirector without redundancy. The name of the machine is ccjlsn01 and all files are accessed by the user applications as:

root://ccjlsn01//store/..../aaaFile.root

As for other sites reasonably low-end hardware is used for the redirector machine. The specifications of the In2p3 redirector machine are:

• Sun 250
• dual ultra sparcII - 450 MHz
• 1GB of memory
• 2GB swap
• Solaris9

The data servers

In2p3 uses a mix of hardware for the data servers as new hardware has been added to the server pool over time. As will be discussed below, In2p3 uses HPSS as the back end mass storage and allows dynamic staging of data. They were the only site besides SLAC to provide access to BaBar data in the (now legacy) Objectivity format and (unlike SLAC) use the same disk cache for both data served by xrootd and by the objectivity AMS (the olbd in fact works with both!). Here is a snapshot of their server pool:

• Sun Netra 1405T (6 of these)
• 4 cpu (ultra sparc II - 440 MHz)
• 1GB RAM
• 2GB swap
• Some Solaris8, some Solaris9
• 2 filesystems of 1TB each

• Sun 450 (2 of these)
• ultra sparc II 450 MHz
• 2 filesystems of 1TB each
• 1GB RAM
• 2GB swap
• Solaris8

• Sun Fire V440 (1 of these)
• ultra sparc III 1.064 GHz
• 1 filesystem of 4TB
• 8GB RAM
• 14GB swap
• Solaris9

• Sun Fire V480 (1 of these)
• ultra sparc III 900 MHz
• 1 filesystem of 4TB
• 8GB RAM
• 8GB swap
• Solaris9

It should also be noted that no issues have arisen as a result of mixing such disparate servers in a single system.

The xrootd and olbd configurations

The config files used at CCIn2p3 are:

• redirectors -

redirector - in2p3_redirector.cf

data servers - in2p3_dataserver.cf

The cache filesystem(s)

(More coming soon....)

Dynamic staging and HPSS

(Coming soon....)

Restarting crashed xrootd and olbd servers

Adding new data to the system

The system described on this web-page provides read-only access to data available from mass-storage (HPSS). New data is added to the system via a separate, dedicated channel that copies the files into HPSS. Once that has happened, the data is then available for read-only access as described on this page.

Software installation

In2p3 uses the same Solaris8 and Solaris9 binary tarballs which are available from the download page for any given xrootd version.

(Coming soon....)

Managing two different access systems (Objy/AMS and root/xrootd)

(Coming soon....)

Last modified 29-Nov-2004, Peter.Elmer@cern.ch