Hi Pat There is not a lot you can do since every commit will force a write to the disk ! You are hitting that limit of the disk that normally is app. 100 - 120 I/O per sek. The only real fix is change the application to do less commit's. It will not help to change the size of the redo log buffer or the redo log files if you have multiple redo log members on the same disk it will help to separate the members to different disk's but it will not fix the design problem of committing for every insert.
Somebody might suggest you to put a chach on the redo log file system but don't this very dangerous since Oracle assumes that writes to disk's are true writes and if you ever had a loss of the chach there is a big chance that your database would loose transactions :-( Pat Howe wrote: >We have a canned package that we use to insert approx 100 records/second >into one table (oltp environment). >Each record is just under 1K (datatypes = number and varchar). >There are several indexes that are build on the table as the records are >inserted. >Each and every record is committed. >Therefore we are flushing the 'redo log buffer' to disk (online redo >logfiles) 100 times per second (once per commit). > >Not surprisingly we have noticed IO waits which we believe are associated >with our 'Redo Log buffer'. Namely ; > log_file_sync = 180 waits/sec > log_file_parallel_write = 180 waits/sec > >We tried resizing the 'redo log buffer' from 16K to 256K - but we did not >notice any improvements. >Neither Log switching or archiving seem to be excessive. >100 records per second seems to be our maximum speed without the application >queuing up and Oracle showing very high waits on log_file_sync and >log_file_parallel_writes. > >Does anyone know how we might be able to minimize the IO waits? > >Thanks in advance. > >ENVIRONMENT >oracle : Oracle 8.1.7.4 >os : Sun Sparc Solaris 8 >box : 8x8 E10K >IO : Hitachi SANS unit through fiber and Brocade switch > > >_________________________ > Patrick J. Howe > > > > > -- /regards Peter Gram Mobil : +45 2527 7107 Fax : +45 4466 8856 Miracle A/S Kratvej 2 2760 Måløv http://miracleas.dk
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