RHEL high percentage of processor time from system 5196

I have a data-intensive set of programs, using IBM's DB2 V8.1.7 (IIRC). I used to run it on a machine with two 10,000 rpm Ultra-2 SCSI hard drives and 512 MBytes RAM. It would take over 10 hours to populate the database from scratch.

I moved it to a faster machine, but the main difference was that I have 4 10,000 rpm Ultra-320 SCSI hard drives on it (and 2 7,200 rpm EIDE(100) hard drives) so it seeks a whole lot less. It also has 4 GBytes ECC DDR RAM. This allowed me to use much larger extent sizes (32 4096 byte pages) and since the Linux kernel that I run permits raw IO to contiguous disk areas, the dbms can do the IO in much larger chunks (an extent at a time). My buffer pool for the date is 102,400,000 bytes, and the buffer pool for the indices is 819,200,000 bytes. This allows the dbms to keep a lot of that stuff in RAM instead of doing IO with it.

That runs now in a bit under two hours.

Note: I could get all the data and indices on one very large single hard drive, but then the seek contention would kill me. So I have the four 18 GByte SCSI drives instead of one bigger one. I have the dbms logfiles on an EIDE(100) drive (that is not used for anything else when this is going on), and it is definately the bottleneck (measured with iostat), so I should move an underused 10,000 rpm Ultra-2 SCSI hard drive from another machine to this one (on the other SCSI controller), but it will be a while before I get around to that.

-- .~. Jean-David Beyer Registered Linux User 85642. V PGP-Key: 9A2FC99A Registered Machine 241939. ^^-^^ 15:20:00 up 7 days, 13:42, 4 users, load average: 4.24, 4.41, 4.36