need to check the database config - esp the sga size compare to the physical
ram (is the sga swapping), check buffer hit ratio, if the app has lots of
writes then raid5 is a poor choice, what's the strip width - compare to db
block size, may need to move redo log, temp table, to non-raid disks
how many disks you have on each scsi channel, what's size of the cache on
the raid device (are they config properly)
there are lots of issues, but start with the nature of the app (perl/dbi is
not very effective) and physical config of the database - ie see if they are
config for each other
cheers and good luck
> ----------
> From: Calvin Lim[SMTP:calvin-lim_at_mediaring.com]
> Reply To: ORACLE-L_at_fatcity.com
> Sent: Thursday, May 04, 2000 11:55 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Oracle on RAID - IOwait problem
>
> Hi,
>
> We've just put a 8.1.5 on a 2CPU Sun Solaris into production.
>
> The machine is hooked on to a RAID5 storage device by Seek.
> Oracle datafiles are spread across 3 channels on the RAID.
> What i'm noticing is that the disk iowait is reaching incredible
> levels and top is reporting 0.0% idle for CPU states and 100M
> swaps.
>
> We're currently suspecting that it could be 1. the RAID
> configuration thats giving problem, 2. some cron driven perl/DBI
> jobs that is pounding the Database too often too hard with
> inefficient queries.
>
> Could 2. be a reason for extensive iowaits thats always hovers
> round the 85% mark. I need some advise on how one would go about
> troubleshooting such iowait related problems? Thanks very much.
>
> Regards,
> Calvin
>
> --------------------
>
> load averages: 0.39, 0.43, 0.46 22:19:30
> 74 processes: 71 sleeping, 1 running, 2 on cpu
> CPU states: 0.0% idle, 5.2% user, 8.5% kernel, 86.3% iowait, 0.0% swap
> Memory: 1024M real, 16M free, 100M swap in use, 1900M swap free
>
> PID USERNAME THR PRI NICE SIZE RES STATE TIME CPU COMMAND
> 2359 root 1 59 0 1944K 1080K sleep 0:03 2.40% sshd1
> 29216 oracle 1 58 0 832M 799M cpu0 1:50 2.12% oracle
> 2383 oracle 1 58 0 2000K 1360K cpu2 0:00 1.24% top
> 29214 mrurl 1 53 2 13M 4840K run 0:54 0.98% ifmxTrigger
> 10591 oracle 1 60 0 834M 798M sleep 102:23 0.95% oracle
> 27178 oracle 1 38 0 2000K 1160K sleep 0:55 0.51% top
> 10360 oracle 1 60 0 832M 798M sleep 113:10 0.50% oracle
> 10362 oracle 1 60 0 832M 797M sleep 112:00 0.49% oracle
> 10366 oracle 1 60 0 832M 797M sleep 111:50 0.42% oracle
> 10364 oracle 1 60 0 832M 798M sleep 112:27 0.41% oracle
> 10368 oracle 1 60 0 832M 797M sleep 112:16 0.38% oracle
> 2389 oracle 1 60 0 831M 799M sleep 0:00 0.19% oracle
> 10338 oracle 1 59 0 833M 794M sleep 3:01 0.15% oracle
> 10340 oracle 1 58 0 832M 794M sleep 4:40 0.14% oracle
> 9341 oracle 1 48 0 8960K 2352K sleep 9:34 0.13% tnslsnr
>
> ----------------
> --
> Author: Calvin Lim
> INET: calvin-lim_at_mediaring.com
>
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Received on Fri May 05 2000 - 13:38:12 CDT
