are you writing your RMAN backups to the same set of disks that you are reading from ? make sure your backups are on different sets of disks. if your on a SAN, ask your administrator to map you out a mount point that maps through the same to a different raid group preferably on a different HBA. alot of SAN guys don't want to put in the effort. Its really just a GUI and will not take alot of time. On Fri, Jul 11, 2008 at 9:18 AM, Finn Jorgensen <finn.oracledba@xxxxxxxxx> wrote: > Brandon, > > Believe me, I've tried to find a time when the backup can run when > nothing else is going on, but even the incrementals take 4-5 hours. > I've added a block change tracking file today, so after this weekend's > full backup that should dramatically reduce the amount of time the > inc's take. > > Jared, the channels is set to 12, but since the database is mostly > this one bigfile tablespace effectively I'm only using 1 channel 99% > of the time. I will read your doc though. > > I'm pretty sure I've not saturated the IO subsystem. With only 1 > channel going I'm getting ~400MB/min for this database. I have other > databases on the same storage using the same backup storage too that > use 8-12 channels and get 1800-2000MB/min. > > My plan is to split this large tablespace into several smaller > tablespaces and use more channels along with the BCT file which will > reduce the time the backup takes so I can avoid running it while the > app runs. However, I think that's a bit of a bandaid. The app > shouldn't slow like that during backups. > > Here's another couple of nuggets from the AWR report if that rings a > bell with anybody : > > Top 5 Timed Events Avg %Total > ~~~~~~~~~~~~~~~~~~ wait Call > Event Waits Time (s) (ms) Time Wait > Class > ------------------------------ ------------ ----------- ------ ------ > ---------- > RMAN backup & recovery I/O 1,652,234 11,557 7 14.7 > System I/O > buffer busy waits 10,628 10,213 961 13.0 > Concurrenc > > Also, the filesystem is Veritas, which I know does not support Asynch > IO natively, however filesystemio_options is set to async. I know > there are many opinions on this parameter out there, but does anyone > have any thoughts on if this is the best value or if I should change > that to setall? > > Thanks again, > Finn > > On Thu, Jul 10, 2008 at 5:30 PM, David Barbour <david.barbour1@xxxxxxxxx> > wrote: > > I have a similar problem, but it's a difference between incrementals and > > full backups. When the full backups run, I've limited the size of the > > backup set and I don't have a performance issue. When the incremental > > backups run however, the application basically comes to a screaming halt. > > We're on AIX 5.3L, Oracle 9.2.0.7 (soon to be upgraded to 10g - thank > you), > > with cio mounted filesystems. Finally got the Sys Admins to mount our QA > > box without CIO and I'm going to test the incremental backups using both > > setall and asynch in the filsystem_io parameter. > > > > > > On Thu, Jul 10, 2008 at 5:14 PM, Jared Still <jkstill@xxxxxxxxx> wrote: > >> > >> On Thu, Jul 10, 2008 at 1:16 PM, Finn Jorgensen < > finn.oracledba@xxxxxxxxx> > >> wrote: > >>> > >>> Checking an AWR report I noticed that the "Av Rd(ms)" column of the > >>> tablespace IO stat for that tablespace is at 671ms (Yikes!) when the > >>> RMAN job is running and a much more normal 3.6ms when it's not. > >>> > >> > >> How many channels are being used? > >> > >> You may want to reduce the # of channels if > 1. > >> > >> You can use the 'SET LIMIT' command to slow down RMAN. > >> (it's mostly undocumented) > >> > >> See "Making RMAN Perform' at http://jaredstill.com/articles.html > >> > >> There's a couple pages on RATE and SET LIMIT > >> > >> -- > >> Jared Still > >> Certifiable Oracle DBA and Part Time Perl Evangelist > > > > > -- > //www.freelists.org/webpage/oracle-l > > >