Robert, I did with both catalog and no catalog mode and in both the case it shows 30,28 minute for the 8G datafile . However when I ran it with optimizer_mode=rule . it did the same file in 24 minutes. but today there is hardly any load on the server so It might not hold true on week day backup. Yes I did with default parallelism(=1) and somehow I could not see any gain . by the way when you say to try to 2 separate disk . do you mean 2 different san mount point . please let me know and I can surely give it a try. Thanks Pk On Sat, Jan 31, 2009 at 10:51 PM, Robert Freeman <robertgfreeman@xxxxxxxxx>wrote: > If ASYNC IO is not supported then your direction to multiple slaves would > be correct. > Did you try the backup of the datafile both connect to the catalog and not > connected? I'm looking to compare the two. > > Have you tried without parallelism? If your disk can't handle the IO then > the two channels may just not be enough. Do you have two separate physical > disks that you could write to at the same time? You may be saturating your > bandwidth with the two channels? > > 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:* Robert Freeman <robertgfreeman@xxxxxxxxx> > *Cc:* ORACLE-L <oracle-l@xxxxxxxxxxxxx> > *Sent:* Saturday, January 31, 2009 11:02:31 PM > > *Subject:* Re: rman backup slow > > 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 >>> >>> >>> >>> >> >> >