javac -classpath /opt/hadoop/hadoop-0.20.2/hadoop-0.20.2-core.jar -d wordcount_classes WordCount.java
"
The DICE Hadoop cluster runs mainly on the DICE Beowulf machines. There are currently about 70 data nodes in the cluster. It runs Hadoop 0.20.2 on Scientific Linux 6.
To get access to the web status pages of the clusters (URLs are given below) you will need to be connecting from a machine on the Informatics network. If you're connecting from outside that network (for instance if your machine is on the University's wireless network) then you may find the OpenVPN service useful.
To get access to the cluster "ssh namenode
" from a machine on the Informatics network. (If this is slow you might find it quicker to "ssh 129.215.18.30
".)
To examine the HDFS status see http://namenode.inf.ed.ac.uk:50070.
To examine the status of Map/Reduce jobs look at http://jobtracker.inf.ed.ac.uk:50030.
If you have a question or a problem to do with the Hadoop cluster contact Computing Support. They'll either answer your question or put you in touch with someone who can.
HadoopCareAndFeeding is a resource for computing staff. It describes how to maintain the cluster.
The overall layout of the Beowulf switches is as follows:
/ core2/A4 3Gb/s Trunk { ^ core2/A5 \ | ^ core2/A6 | | ^ | | | core1/A4 (redundant | | | ^ link) | | | | | | | | Switch bw00 (HP ProCurve 2824) | | | | +-------------------------------------+--+--+--+-+ | ... beowulf nodes ... 17 18 19 20 21 22 23 24 | +-------------------------+--+--+--+-------------+ | | | | 2Gb/s Trunk | | | | 2Gb/s Trunk +------+ | | +-------------------------+ | +------+ +-------------------------+ | | | | | +-------------------------+--+-+ +-------------------------+--+-+ | ... beowulf nodes ... 49 50 | | ... beowulf nodes ... 49 50 | +------------------------------+ +------------------------------+ Switch bw01 (HP ProCurve 2650) Switch bw02 (HP ProCurve 2650)
Each individual port and link in this picture - each inter-switch connection - runs at 1Gb/s.
So there is a trunked link giving 3Gb/s back to the core from bw00, (the other link back to the core is a redundant link back - it will normally be blocked by STP), and two trunks from bw00 - one each to bw01 and bw02 - giving 2Gb/s.
There is no direct connection between bw01 and bw02.
bw00 is an HP ProCurve 2824. It has a total port count of 24, and its backplane runs at 48 Gb/s. All of its ports run at 1Gb/s.
bw01 and bw02 are HP ProCurve 2650 switches. Each has a total port count of 50, and the backplane of each runs at 13.6 Gb/s. Their inter-switch connection ports run at 1GB/s, but the ports to which the nodes are connected run at 100Mb/s.
Each machine has a connection to two subnets, 129.215.18 and 129.215.81. Hadoop is configured to prefer using the former.
The backplane speeds give the total capacity of each switch.
A note about trunks: the capacities (3Gb/s or 2Gb/s in the above) give the total capacity of the trunked link, but each individual connection over the trunked link always uses one cable only (which one, depends on the sending and receiving MAC addresses), so each individual connection over any of the above trunks can run at a maximum of 1Gb/s.
There are scenarios where the trunk links bw00<->bw01 and bw00<->bw02 could be swamped: it just depends on which ports are wanting to talk to which others, and at what data rates.
You can see usage statistics for all of the above at http://netmon.inf.ed.ac.uk/BW.html.
All of the spare desktops are connected to the single switch 'sr99', an HP ProCurve 2610-48 (the HP part number for which is J9088A.) That switch has 48 10/100Base-TX ports, 2 10/100/1000 ports, and two open GBIC slots.
So: each desktop has a 100Mb/s link to the switch, and the switch currently has two 1Gb/s uplinks to core switch 'core2' (the same core switch to which switch bw00 on the Beowulf rack is uplinked), configured as a single 2Gb/s trunk uplink.
Therefore:
Visually:
/ core2/A17 2Gb/s Trunk { ^ \ | core2/C17 | ^ | | | | +----------------------------------------------+--+-----+ | 1 2 ... ... ... ... ... ... ... 47 48 | 49 50 | | <--- Hadoop nodes - all 100Mb/s ----> | 1Gb/s uplinks | +-------------------------------------------------------+ Switch sr99 (HP ProCurve 2610-48)