LFC Notes

Introduction

The LFC provides the file catalog for mapping between logical file names and the physical data location on storage elements.

The LFC participates in the following flows

Data

The LFC consists of

  • An oracle database GRID7
  • A daemon lfcdaemon which handles user requests

Configuration

It is planned to have one instance of LFC for each VO. Some VOs want the master LFC to be at CERN, others want just the LFC for the data held at CERN. From the infrastructure architecture, these cases are identical except for the capacity issues.

From the criticality perspective, the VOs which require their CERN LFC to be the master for all their application increases the criticality.

High Availability

If the LFC is down, the impact is as follows

  • No files can be read from the site / globally depending on VO configuration
  • No new files can be stored

Approach LFC

The LFC and FTS follow similar architectures.

The LFC will be constructed as

  • Front end servers performing the application
  • Backend databases stored on Oracle RAC providing reliable database services
  • DNS Load Balancing of the lfc alias

Equipment required

Approach 1

Assuming 4 VOs and a general LFC,

Component Number Purpose
Midrange Server 10 masters and standby machines
FC HBA 10 Fibre channel connectivity
FC Switch Ports 20 Connectivity for the two servers
FC Disk space 1000 Storage for LFC database on different disk subsystems)

Engineering required

Development Purpose
Start/Stop/Status procedure Scripts for LFC operations
Lemon LFC availability test A lemon aware sensor which can be used for reporting availability.
Lemon components availability test A lemon aware sensor which can be used for reporting availability. Tests for GridFTP processes would be required.
Linux Heartbeat availability test A Linux-HA aware sensor which would activate the procedure for automatic switch from master to slave
Switch procedure Automatic switch from master to slave changing the DNS alias, disabling the master, enabling the slave in its new master role
Capacity Metric Capacity metrics defined for
Number of transfers/second
Quattor configuration for Linux-HA NCM component to configure Linux-HA/Heartbeat

Questions

Nr Description Status Open Date Who Log
1 Is round robin feasible ? Is the only state information in the database closed 2005/09/21 Tim Yes

-- TimBell - 21 Sep 2005

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Topic revision: r2 - 2005-11-02 - TimBell
 
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