[GE users] mysql path + arco issues

crhea crhea at mayo.edu
Mon Feb 16 20:39:15 GMT 2009

On Fri, Feb 13, 2009 at 08:53:29AM +0100, aja wrote:
> http://gridengine.sunsource.net/howto/arco/arco_mysql.txt ?
> You can find useful information there.
> Especially, do not forget to configure MySQL server to use InnoDB as the 
> default storage engine!
> Regards,
> aja

A question and an issue for the Arco gurus...

1. Back when we installed Arco, the install guide made little distinction 
   on the engine used for MySQL. From Aja's comments above, it appears that
   this is a big deal. What features/engine characteristics is Arco 
   using where InnoDB matters over the default (MyISAM)?

   (My current cluster/Arco uses MyISAM and I want to understand if 
   it's worth it to convert the tables to InnoDB...)

2. If dbwriter dies (for whatever reason), we've seen that the cleanup process
   never catches up. In poking around, we see (for example):

   SELECT hv_id FROM sge_host_values WHERE hv_time_end < '2008-02-16 14:00:00' limit 500

    as a sub-select of a DELETE. Why is the SQL code structured this way?
    On a small-medium cluster (100 nodes/400 CPUs) the sub-select can take
    several minutes to run (our sge_host_values table is 110M rows). 
    Why limit each sub-select to 500?  When we get into this state, the 
    cleanup never catches up and thrashes the DB.  I go in by hand and 
    run the delete with a WHERE clause (no sub-select, no limit). 


-- Cris

 Cristopher J. Rhea                     
 Mayo Clinic - Research Computing Facility
 200 First St SW, Rochester, MN 55905
 crhea at Mayo.EDU
 (507) 284-0587


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