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New in This Release
MapR 2.0 provides job and task analytics. The MapR Metrics service collects and displays analytics information about the Hadoop jobs, tasks, and task attempts that run on the nodes in your cluster. You can use this information to examine specific aspects of your cluster's performance at a very granular level, enabling you to monitor how your cluster responds to changing workloads and optimize your Hadoop jobs or cluster configuration. This information is available both in the Jobs area of the MapR Control System and via the Metrics API. MapR Metrics requires a SQL server to store metrics data.
MapR services can be configured globally across the cluster, from master configuration files stored in a MapR-FS, eliminating the need to edit configuration files on all nodes individually. See Central Configuration.
MapR's Centralized Logging feature provides a job-centric view of all log files generated by tracker nodes throughout the cluster. During or after execution of a job, use the maprcli job linklogs command to create a centralized log directory populated with symbolic links to all log files related to tasks, map attempts, and reduce attempts pertaining to the specified job(s). If MapR-FS is mounted using NFS, you can use standard tools like grep and find to investigate issues which may be distributed across multiple nodes in the cluster.
maprinstall script automates the process of installing and starting MapR services on a single node or multiple nodes. The
maprinstall script can take command-line arguments or interactive input about how to proceed with the installation.
Running as Non-root User
MapR services can now run as a user other than
root, enabling greater security and compliance with SELinux. During installation, you can choose or create a user under which MapR services run; after upgrade to Version 2.0, you can convert a cluster from running as
root to a non-
Metrics information about each node in the cluster is available through the node metrics API.
MapR now supports the HCatalog metadata and data storage abstraction service to provide interoperability across the Pig, MapReduce, and Hive services.
- (Issue 5830) - After a disk failure, MFS may access a non-existent disk and expose a Linux kernel panic
- (Issue 6592) - MFS thinks a volume is not mounted, while it in fact is mounted, which may lead to MapReduce task failures
- (Issue 6724) - Under heavy I/O load on multiple volumes with readahead, MFS may core dump due to null-pointer assert failure
- (Issue 7422) - MFS may not "heartbeat" to CLDB for more than 5 minutes due to FSID mismatch, resulting in errors in MFS and CLDB logs
- (Issue 7630) - Permission denied on relative path
Rare MapR application crashes due to Java JVM dumping core. This is a Java Runtime Environment issue.
In some cases, Map/Reduce preemption may not work with Map Task prefetch and Expresslane. MapR recommends using prefetch, preemption and expresslane mutually exclusively.
The bug https://issues.apache.org/jira/browse/HIVE-2907 is not yet fixed in MapR's release. It may cause the dropping of a table with a large number of partitions to fail due to an out-of-memory error.
There are no obvious indications when a MapR license expires, except the degradation of services to the non-licensed level. The workaround is to pay attention to License expiration alarms before the actual expiry.
When a node's IP number is reassigned to another node, remote procedure calls are misdirected to the wrong node. This can result in widespread errors affecting any system that use the RPC binding layer, including container resync operations that never finish or the creation of several superfluous containers. Restart the cluster to clear this condition.
If you use the latest version of any browser to view the MCS, the CLDB, HBase, JobTracker, and job log pages do not load when you click on the respective links. As a workaround, use the following instructions to disable mixed-content-blocking in your browser:
Scroll to the bottom of the screen, and click Show all content. The page refreshes and displays mixed content.
- At the top of the page, to the left of the address bar, click (the shield icon).
- In the pop-up window that appears, click the down arrow next to "Keep Blocking", and select Disable Protection on This Page. The page refreshes and displays mixed content. The shield icon is replaced with a warning symbol to indicate that the page is displaying both secure and non-secure items.
- Click (the shield icon) on the right side of the address bar.
- In the icon dialog box, click Load anyway. The page refreshes and displays mixed content. The URL in the address bar shows https crossed out to indicate that the page is displaying both secure and non-secure items.