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The LOFAR Cluster
This page describes the LOFAR cluster for (potential) users. The cluster is used to store the correlated data from the BlueGene and to run pipelines that do the “standard” reduction and calibration. After this pipeline processing, the results are stored in the Lofar Export (staging) Archive.
We welcome authorized users on this cluster. For the time being the users are bound to only a part of the cluster. This part is called a subcluster. Various users groups have been granted access to a specific subcluster. Users can utilized a standard login environment (see below) and they can access the cluster resources using one of the two frontends “lfe001” and “lfe002”.
LOFAR Cluster layout (brief)
The Lofar cluster is devided into 8 subclusters. Each subcluster is a processing cluster for a specific commsissioning group. There are 72 compute nodes and 24 storages in total. Each subcluster has 9 compute nodes and 3 storage nodes of 24TB raw capacity. The storage nodes have 4 RAID5 partitions each. A partition holds a single XFS filesystem. Each filesystem is NFS mounted on all 9 compute nodes. So 1 compute node has 12 NFS data volumes mounted.
Portal
You can access the Lofar cluster through the portal: “ssh -X portal.lofar.eu” We maintain a ssh whitelist, so only known institutes are able to login. Please send an email to grit at astron.nl or h.paas at rug.nl to add your institute or personal IP number. Once logged in, you'll find an empty home directory. You'll have to login at one of the two frontends “lfe001” of “lfe002” using “ssh -X”. When you don't know which one, please use “lfe001” by default.
Frontend
A frontend has 2 Intel Xeon L5420 quad core processors, 16GB internal meomory, 2 GbE interfaces and 2TB disks in RAID5 configuration. There are actually two identical frontends. Both of them serve a specific group of subclusters. The frontends are used to build the software and regulate the workload on the subclusters. There is a page that describes the frontend in detail
Processing units
The compute elements have 2 Intel Xeon L5420 quad core processors, 16GB internal meomory, 2 GbE interfaces and 1TB disks in RAID0 configuration. They can be accessed by secure shell and they are grouped.
Storage Units
The storage nodes are HP DL180G5 boxes, having 2 Intel Xeon L5420 quad core processors, 16GB internal memory, 6 GbE network interfaces and 24TB disks. The disks are devided into 4 partitions of 6 disks each, set up in RAID5 configuration. The XFS filesystems are called “/data1” till “/data4”.
Available Subclusters
The current subcluster assignment is:
lfe001:~> showsub
This script shows the subcluster definitions
sub lce-nodes lse-nodes cexec-lce cexec-lse In use for: ==== ========= ========= ========= ========= =========== sub1 lce001-lce009 lse001-lse003 lce:0-8 lse:0-2 production group sub2 lce010-lce018 lse004-lse006 lce:9-17 lse:3-5 no power sub3 lce019-lce027 lse007-lse009 lce:18-26 lse:6-8 imaging group sub4 lce028-lce036 lse010-lse012 lce:27-35 lse:9-11 no power sub5 lce037-lce045 lse013-lse015 lce:36-44 lse:12-14 pulsar group sub6 lce046-lce054 lse016-lse018 lce:45-53 lse:15-17 no power sub7 lce055-lce063 lse019-lse021 lce:54-62 lse:18-20 developers group sub8 lce064-lce072 lse022-lse024 lce:63-71 lse:21-23 no power
User Access
Access through portal to Cluster frontend
LOGIN environment
Do and Don'ts
Old Stuff
Offline processing clusters
The disks of the offline storage nodes are NFS mounted on all these offline nodes. These systems are in use for offline processing (i.e. when data has been transfered from the central storage facility).
The clusters are described on more detail on this page. See this page for more information on the login environment.
Offline storage cluster
This cluster acts as a temporary data buffer. Data is copied from the online storage systems to these systems, so that the online systems can be used to store new data. These systems are accessable from the offline processing clusters, allowing post-processing of the data. More information can be found on this page.