Wednesday, October 5, 2011
Friday, September 2, 2011
Thursday, March 3, 2011
Exalogic includes a tool called DCLI (Distributed Command Line Interface) that can be used to run the same commands on all or a subset of compute nodes in parallel. This saves a lot of time and helps avoid the sorts of silly errors that often occur when running a command over and over again. DCLI is a tool that originally came with Exadata (as documented in the Oracle Exadata Storage Server Software User's Guide - E13861-05 chapter 9), and is now incorporated into the new Exalogic product too. It is worth noting that if you are ever involved in performing the initial configuration of a new Exalogic rack, using OneCommand to configure the Exalogic's networking, then under the covers OneCommand will be using DLCI to perform a lot of its work.
Introduction to Exalogic's DCLI
The Oracle Enterprise Linux 5.5 based factory image running on each Exalogic compute node has the exalogic.tools RPM package installed. This contains the DCLI tool in addition to other useful Exalogic command line utilities. Running 'rpm -qi exalogic.tools' on a compute node shows the following package information:
Name : exalogic.toolsWhen you run 'rpm -ql exalogic.tools' you will see that the set of command line utilities are all placed in a directory at '/opt/exalogic.tools'. Specifically, the DCLI tool is located at '/opt/exalogic.tools/tools/dcli'.
Version : 126.96.36.199
Release : 1.0
Now run the DCLI command with the '-k' option as shown below which pushes the current user's SSH public key to each other compute node's '.ssh/authorized_keys' file to establish SSH Trust. You will again be prompted to enter the password for each compute node, but this will be the last time you will need to. With the '-k' option, each compute node is contacted sequentially rather than in parallel, to give you chance to enter the password for each node in turn.
You can then run the original date-time test again, to satisfy yourself that SSH Trust and User Equivalence is indeed established between the master compute node and each other compute node and that no passwords are prompted for.
# /opt/exalogic.tools/tools/dcli -t -g nodeslist /bin/date
Now lets have a look at some examples common DCLI commands you might need to issue for your new Exalogic system.
# /opt/exalogic.tools/tools/dcli -t -g nodeslist groupadd -g 500 oracle
# /opt/exalogic.tools/tools/dcli -t -g nodeslist useradd -g oracle -u 500 oracle
echo welcome1 | passwd root --stdin
echo welcome1 | passwd oracle --stdin
# chmod u+x setpasswds.scl
# /opt/exalogic.tools/tools/dcli -t -g nodeslist -x setpasswds.scl
# /opt/exalogic.tools/tools/dcli -t -g nodeslist chown -R oracle:oracle /u01/common/general
# vi addmount.scl
cat >> /etc/fstab << EOF
el01sn-priv:/export/common/general /u01/common/general nfs rw,bg,hard,nointr,rsize=131072,wsize=131072,tcp,vers=3 0 0
# chmod u+x addmount.scl
# /opt/exalogic.tools/tools/dcli -t -g nodeslist mount /u01/common/general
In the default Exalogic set-up, DCLI executes as root user when issuing all of its commands regardless of what OS user's shell you use to enter the DCLI command from. Although root access is often necessary for creating things like OS users, groups and mount points, it is not desirable if you just want to use DCLI to execute non-privileged commands under a specific OS user on all computes nodes. For example, as a new 'coherence' OS user, you may want the ability to run a script that starts a Coherence Cache Server instance on every one of the compute nodes in the Exalogic rack, in one go, to automatically join the same Coherence cluster.
Sunday, January 23, 2011
- Increased server scalability, throughput and responsiveness. Improvements to the networking, request handling, memory and thread management mechanisms, within WebLogic and JRockit, enable the products to scale better on the high-multi-core compute nodes that are connected to the fast InfiniBand fabric. WebLogic will use Java NIO based non-blocking server socket handlers (muxers) for more efficient request processing, multi-core aware thread pools and shared byte buffers to reduce data copies between sub-system layers. Coherence also includes changes to ensure more optimal network bandwidth usage when using InfiniBand networking.
- Superior server session replication performance. WebLogic's In-Memory HTTP Session Replication mechanism is improved to utilise the large InfiniBand bandwidth available between clustered servers. A WebLogic server replicates more of the session data in parallel, over the network to a second server, using parallel socket connections (parallel "RJVMs") instead of just a single connection. WebLogic also avoids a lot of the unnecessary processing that usually takes place on the server receiving session replicas, by using "lazy de-serialisation". With the help of the underlying JRockit JVM, WebLogic skips the host node's TCP/IP stack, and uses InfiniBand's faster “native” networking protocol, called SDP, to enable the session payloads to be sent over the network with lower latency. As a result, for stateful web applications requiring high availability, end-user requests are responded to far quicker.
- Tighter Oracle RAC integration for faster and more reliable database interaction. For Exalogic, WebLogic includes a new component called “Active Gridlink for RAC” that provides application server connectivity to Oracle RAC clustered databases. This supersedes the existing WebLogic capability for Oracle RAC connectivity, commonly referred to as “Multi-Data-Sources”. Active Gridlink provides intelligent Runtime Connection Load-Balancing (RCLB) across RAC nodes based on the current workload of each RAC node, by subscribing to the database's Fast Application Notification (FAN) events using Oracle Notification Services (ONS). Active Gridlink uses Fast Connection Failover (FCF) to enable rapid RAC node failure detection for greater application resilience (using ONS events as an input). Active GridLink also allows more transparent RAC node location management with support for SCAN and uses RAC node affinity for handling global (XA) transactions more optimally. Consequently, enterprise Java applications involving intensive database work, achieve a higher level of availability with better throughput and more consistent response times.
- Reduced Exalogic to Exadata response times. When an Exalogic system is connected directly to an Exadata system (using the built-in Infiniband switches and cabling), WebLogic is able to use InfiniBand's faster “native” networking protocol, SDP, for JDBC interaction with the Oracle RAC database on Exadata. This incorporates enhancements to JRockit and the Oracle Thin JDBC driver in addition to WebLogic. With this optimisation, an enterprise Java application that interacts with Exadata, is able to respond to client requests quicker, especially where large JDBC result sets need to be passed back from Exadata to Exalogic.