Lengthening backup
- From: "Terry Sutton" <terrysutton@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 7 Jul 2006 11:05:14 -0700
I'm having some issues with a client's RMAN backup. They're on Oracle 8.1.7.4,
Solaris 8. It's a weekly full backup, and they're backing up ~1.5TB to disk,
and the longer the instance is up, the longer the backup takes. A recent
progression has been:
Week 1: 15 hours
Week 2: 16 hours
Week 3: 19 hours
Week 4: 21 hours
Week 5: 25 hours
...
Week 15: 48 hours
But when we bounce the database, the length of time to backup goes back to ~15
hours. The database size fluctuates a bit, with a bit of an upward trend, but
not with a significant change in size.
One time, when the backup had been running for 24.5 hours, I checked the
session stats for the session on the database which is performing the backup,
and these were the stats:
Sess Total Total Time (hs) Avg (hs)
ID Wait Event Waits Timouts Waited Wait
----- ------------------------------------- -------- ------- --------- --------
436 CPU time 4157966
436 SQL*Net message from client 9165 0 471612 51
436 enqueue 1226 238 89874 73
436 rdbms ipc reply 4767 219 52585 11
436 db file sequential read 2782 0 5621 2
436 latch free 95 75 3837 40
436 control file parallel write 6519 0 1865 0
436 control file sequential read 114550 0 1366 0
436 db file single write 915 0 242 0
436 file open 10104 0 201 0
436 file identify 1830 0 30 0
436 SQL*Net message to client 9165 0 2 0
I also checked the stats for the session on the RMAN catalog which is connected
from the main database for the backup:
Sess Total Total Time (hs) Avg (hs)
ID Wait Event Waits Timouts Waited Wait
----- ------------------------------------- -------- ------- --------- --------
11 SQL*Net message from client 3334 0 4281 1
11 CPU time 429
11 db file sequential read 172 0 82 0
11 db file scattered read 69 0 53 1
11 free buffer waits 1 0 21 21
11 SQL*Net message to client 3335 0 1 0
11 latch free 1 1 1 1
11 log file sync 1 0 1 1
11 SQL*Net break/reset to client 2 0 0 0
11 SQL*Net more data from client 1 0 0 0
11 SQL*Net more data to client 16 0 0 0
11 file open 2 0 0 0
The backup script is:
run {
allocate channel d1 type disk format='/sharevol3/orabkup/DBNAME/db_t%t_s%s_p%p'
;
backup
tag full_us2
filesperset 1
database include current controlfile;
release channel d1;
}
I don't have experience tuning RMAN backups, so there may be settings which are
not optimal, but it seems pretty strange that the time would increase the
longer the instance has been up.
Any comments or ideas would be welcome, other than 1) get better hardware or 2)
upgrade to new Oracle version. :-)
--Terry
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