Home » RDBMS Server » Backup & Recovery » Why Oracle generates one more backup piece on one backupset? (Solaris on SPARC, ORACLE 10.2)
Why Oracle generates one more backup piece on one backupset? [message #530974] Fri, 11 November 2011 11:08 Go to next message
edgefree
Messages: 30
Registered: July 2010
Location: Toronto
Member
Hi Gurus,

I ran into a tough issue, and did Google and search here, I could not find the solution. Wish you could help me out!

I set 'maxopenfiles 4' when allocating channel to sbt in my products env, I got 2 backup pieces in one backup set because that tablespace has 7 datafiles. Other configuration is kept as default, such as no maxsize, no MAXPIECESIZE, and etc setting.

I read document from Oracle. It says:"By default a backup set contains one backup piece. To restrict the size of each backup piece, specify the MAXPIECESIZE option of the CONFIGURE CHANNEL or ALLOCATE CHANNEL commands. " And also, maxopenfiles configure does not force another backup piece generated. So, why do I get another backup piece?

BTW, I tried this on another testing environment. I only get one backup piece even there are more than 2 times maxopnefiles datafiles.

Could you please give me an idea to help me out since one more backup piece causing our backup failed with 3rd party backup SW.

Thank you very much in advance!

Edgy
Re: Why Oracle generates one more backup piece on one backupset? [message #530978 is a reply to message #530974] Fri, 11 November 2011 11:32 Go to previous messageGo to next message
Michel Cadot
Messages: 58856
Registered: March 2007
Location: Nanterre, France, http://...
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Copy and paste what you did and got.

Regards
Michel
Re: Why Oracle generates one more backup piece on one backupset? [message #530985 is a reply to message #530978] Fri, 11 November 2011 11:56 Go to previous messageGo to next message
edgefree
Messages: 30
Registered: July 2010
Location: Toronto
Member
Here is some logs:
----------------------------
RMAN> run {allocate channel c1 device type 'sbt_tape' maxopenfiles 6 parms='BLKSIZE=32768 SBT_LIBRARY=/oracle/qa/102/lib/libobk.so';
2> backup check logical tablespace 'CR';
3> }
4>
allocated channel: c1
channel c1: sid=129 devtype=SBT_TAPE
channel c1: Backup/Restore API
Starting backup at 11-NOV-11
channel c1: starting full datafile backupset
channel c1: specifying datafile(s) in backupset
input datafile fno=00008 name=/oracle/qa/sapdata1/cr_1/cr.data1
input datafile fno=00026 name=/oracle/qa/sapdata3/cr_7/cr.data7
input datafile fno=00027 name=/oracle/qa/sapdata3/cr_8/cr.data8
input datafile fno=00010 name=/oracle/qa/sapdata2/cr_3/cr.data3
input datafile fno=00013 name=/oracle/qa/sapdata4/cr_6/cr.data6
input datafile fno=00012 name=/oracle/qa/sapdata3/cr_5/cr.data5
channel c1: starting piece 1 at 11-NOV-11
channel c1: finished piece 1 at 11-NOV-11
piece handle=fsmrdebe_1_1 comment=API Version 2.0,MMS Version 8.1.3.0
channel c1: backup set complete, elapsed time: 00:04:55
channel c1: starting full datafile backupset
channel c1: specifying datafile(s) in backupset
input datafile fno=00009 name=/oracle/qa/sapdata1/cr_2/cr.data2
input datafile fno=00011 name=/oracle/qa/sapdata2/cr_4/cr.data4
channel ch1: starting piece 1 at 11-NOV-11
-------------
When generating 2nd backup piece, it got error to fail create files and then quit.

Please check and help!
Re: Why Oracle generates one more backup piece on one backupset? [message #530986 is a reply to message #530985] Fri, 11 November 2011 11:58 Go to previous messageGo to next message
BlackSwan
Messages: 22688
Registered: January 2009
Senior Member
>Please check and help!
check what?

>When generating 2nd backup piece, it got error to fail create files and then quit.
Why did you decide NOT to share with us the actual & complete error?

It would be helpful if you followed Posting Guidelines - http://www.orafaq.com/forum/t/88153/0/
Re: Why Oracle generates one more backup piece on one backupset? [message #530991 is a reply to message #530986] Fri, 11 November 2011 12:12 Go to previous messageGo to next message
edgefree
Messages: 30
Registered: July 2010
Location: Toronto
Member
Sorry for misunderstanding.

The log I list here is full log I got in this morning testing. It does not show the failure error, I am also confused. However, last time, I did see the error about failed to create 2nd backup piece on 3rd party software log.
Re: Why Oracle generates one more backup piece on one backupset? [message #530997 is a reply to message #530991] Fri, 11 November 2011 12:27 Go to previous messageGo to next message
Michel Cadot
Messages: 58856
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
So we can't help you.

Regards
Michel
Re: Why Oracle generates one more backup piece on one backupset? [message #531274 is a reply to message #530974] Mon, 14 November 2011 20:49 Go to previous messageGo to next message
edgefree
Messages: 30
Registered: July 2010
Location: Toronto
Member
Hi Gurus,

I was feeling so sorry to helpless. I was telling the truth and list the file and log I got, I didn't try to hide and mislead you.

Fortunately, I found the root cause (at least I thought). I'd like to share here anyway.

All this happy is related to Oracle optimization about DISKRATIO. By default, DISKRATIO=4 if no anywhere to set diskratio or FILEPERSET. And another condition is all datafiles are distributed on different disks. This is about the advanced algorithm of backup set.

Here is the link to Oracle document on 9.2. Others are similar.

http://docs.oracle.com/cd/B10501_01/server.920/a96566/rcmconc1.htm#476761

I did the test in my box. It did work and generate only one backup piece when setting DISKRATIO=0 to disable this feature.

Hope it would be helpful for you.

Edgy
Re: Why Oracle generates one more backup piece on one backupset? [message #531296 is a reply to message #531274] Tue, 15 November 2011 01:17 Go to previous message
Michel Cadot
Messages: 58856
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Thanks for the feedback, it will surely be useful and it is appreciated.

Regards
Michel
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