Hi Robert, I did as you suggested with no catalog . it took 30 minutes for a 8GB datafile .which still doesnot look that good ? There is no major db size change in last few quarters . it is just that recently it is overlapping with the business hours once in a while. The backup goes to one disk device . we are using 2 channel . I have yet to find out the disk io rate.so far I have been trying from Oracle side to see if any improvement can be done. The current current vxfs fs does not support async_io . as the way for us to make it use async io is to use ODM or quick i/o and both are not easy option at this time for this 9i database so hoping enabling multiple slave will reduce async io wait. Pleae let me know if I miss anything. thanks Pk On Sat, Jan 31, 2009 at 4:42 PM, Robert Freeman <robertgfreeman@xxxxxxxxx>wrote: > Do a backup without the catalog. Does it go faster? You can start by just > testing the backup of a specific datafile with and without the catalog, > rather than the whole database. I'd do one that is big enough to give you a > decent backup run time. > > Has this database gotten bigger over time or is it's size static? Is the > increased run time of the backup related to any increase in database size? > > Are you just backing up to one disk device? Are you using one channel or > multiple channels? What is the disk IO rate for writes in ms? Are you > getting the throughput you need on your disks. > > I would not change the parameters you are talking about just yet. It would > be much smarter to figure out for sure what is causing your problem before > you change lots of parameters and potentially make the problem even worse. > > I assume that your system does ASYNC IO? Correct? I would not go the SYNC > IO path as you are suggesting by setting disk_asynch_io to false. > > > RF > > Robert G. Freeman > Author: > OCP: Oracle Database 11g Administrator Certified Professional Study Guide > (Sybex) > Oracle Database 11g New Features (Oracle Press) > Portable DBA: Oracle (Oracle Press) > Oracle Database 10g New Features (Oracle Press) > Oracle9i RMAN Backup and Recovery (Oracle Press) > Oracle9i New Features (Oracle Press) > Other various titles out of print now... > Blog: http://robertgfreeman.blogspot.com > The LDS Church is looking for DBA's. You do have to be a Church member in > good standing. A lot of kind people write me, concerned I may be breaking > the law by saying you have to be a Church member. It's legal I promise! :-) > > ------------------------------ > *From:* Prasad <p4cldba@xxxxxxxxx> > *To:* ORACLE-L <oracle-l@xxxxxxxxxxxxx> > *Sent:* Friday, January 30, 2009 9:45:46 PM > *Subject:* Re: rman backup slow > > my apologies for the late response. To answer this . not it is not a > new database . it has been in production since last couple of years. it > hosts a application which has lot of LONG RAW data . it is right now 170GB . > out of which the LONG RAW table only occupies 80GB. The RMAN backup is > taken connected to recover catalog . The backup goes to disk . right now > the cursor_sharing is set to similar . The most significant wait I see is > disk async i/o . This is a solaris server with vxfs and it do not support > async i/o . > > The puzzling factor is the select on x$dual which just sits silently for > hours. and the entire backup duration goes beyond 10 hour . > > This is what we are planning to do increase the db_writer_process from 1 > to 4 and set the disk_asynch_io to false ( i gues the default is TRUE) . > would appreciate your thoughts on this change . > > because of the sensitivity of the application ( it is a highly visible > production database) it is a bit hard to find time to take a no catalog > backup and also do any tracing experiment . but i guess it seems > unavoidable . > > hopefully I didnt miss to provide any information asked. please feel free > to let me know if any further information will assist finding solution. > > Thanks again . > > thanks > Prasad > > >> >> >> On Jan 30, 2009, at 1:10, Prasad <p4cldba@xxxxxxxxx> wrote: >> >> All, >> >> we have a 170G db on 9.2.0.7(solaris 9) . and I see that it currently is >> taking nearly 10 hour+ to do a rman backup . when I see this in grid >> control I see the rman session keeps waiting on this sql . >> >> SELECT >> TO_CHAR(SYSDATE,:"SYS_B_0",:"SYS_B_1"),TO_CHAR(SYSDATE,:"SYS_B_2",:"SYS_B_3"), >> TO_CHAR(SYSDATE,:"SYS_B_4",:"SYS_B_5") FROM X$DUAL >> >> anyone has any similar situation . appreciate any suggestion. >> >> Thanks in advance >> >> thanks >> Prasad >> >> >> >> > >