[Hadoop Wiki] Update of "Hbase/FAQ" by MaximVeksler

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The "Hbase/FAQ" page has been changed by MaximVeksler.
http://wiki.apache.org/hadoop/Hbase/FAQ?action=diff&rev1=66&rev2=67

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  '''''hbase''' is the user under which HBase is running''. To test the configuration reboot and run '''ulimit -n'''
  
- You may also need to edit /etc/sysctl.conf, relevant configuration '''fs.file-max''' See http://thedaneshproject.com/posts/how-to-increase-total-file-descriptors-count-on-linux/
+ You may also need to edit /etc/sysctl.conf, relevant configuration '''fs.file-max''' See http://serverfault.com/questions/165316/how-to-configure-linux-file-descriptor-limit-with-fs-file-max-and-ulimit/
  
  The math runs roughly as follows: Per column family, there is at least one mapfile and possibly up to 5 or 6 if a region is under load (lets say 3 per column family on average).  Multiply by the number of regions per region server.  So, for example, say you have a schema of 3 column familes per region and that you have 100 regions per regionserver, the JVM will open 3 * 3 * 100 mapfiles -- 900 file descriptors not counting open jar files, conf files, etc (Run 'lsof -p REGIONSERVER_PID' to see for sure).