RE: RMAN question(s)
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: <robertgfreeman@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 17 Sep 2007 16:09:34 -0700
In case anyone is interested - I did a test of the 10g "as compresssed"
backupset on a 285GB databases and here are the results:
W/O Compression: backup size = 280GB, backup time = 2 to 10 hours with
an average of about 7.5 hours over the past 3 months (this goes to a
disk staging area and later to tape on a Netbackup server with a LOT of
other backup activity so there is a wide variance in backup times
depending on what else is running at the same time)
W/ Compression: backup size = 36GB, backup time = 2.9 hours (only tested
once so far)
So, I can't really make any conclusions on the backup time yet due to
the large variance in backup times on this environment, but it's clear
that the space savings was significant (280-36=244 & 244/280=87%
reduction) and the runtime from this one sample was close to the bottom
of the normal range so that's promising.
Here are the details of the test environment: AIX 5.3, Oracle 10.2.0.2,
Netbackup 5.1 MP4, BaanIV ERP application data
Regards,
Brandon
Here is the raw data:
SQL> select handle, status, start_time, round(elapsed_seconds/60/60,1)
HRS, round(bytes/1024/1024/1024) GB, compressed from v$backup_piece
where start_time > sysdate-90 order by 3
HANDLE S START_TIME HRS
GB COM
---------------------------------------- - --------------- ----------
---------- ---
baantest_db_3_1_627820117 A 13-JUL-07 10:28 1.8
88 NO
baantest_db_4_1_627820117 A 13-JUL-07 10:28 1.8
90 NO
baantest_db_2_1_627820117 A 13-JUL-07 10:28 1.8
91 NO
c-1234567890-20070713-00 A 13-JUL-07 12:17 0
0 NO
baantest_db_14_1_628542124 A 21-JUL-07 19:02 9.2
90 NO
baantest_db_12_1_628542123 A 21-JUL-07 19:02 9.2
88 NO
baantest_db_13_1_628542124 A 21-JUL-07 19:02 9.2
91 NO
c-1234567890-20070722-00 A 22-JUL-07 04:15 0
0 NO
baantest_db_16_1_629147088 A 28-JUL-07 19:04 8.9
88 NO
baantest_db_18_1_629147089 A 28-JUL-07 19:04 9
90 NO
baantest_db_17_1_629147088 A 28-JUL-07 19:04 9
91 NO
c-1234567890-20070729-00 A 29-JUL-07 04:06 0
0 NO
baantest_db_20_1_629751899 A 04-AUG-07 19:05 9.5
88 NO
baantest_db_22_1_629751899 A 04-AUG-07 19:05 9.7
90 NO
baantest_db_21_1_629751899 A 04-AUG-07 19:05 9.7
91 NO
c-1234567890-20070805-00 A 05-AUG-07 04:48 0
0 NO
baantest_db_24_1_630356804 A 11-AUG-07 19:06 8.9
88 NO
baantest_db_26_1_630356804 A 11-AUG-07 19:06 9.1
90 NO
baantest_db_25_1_630356804 A 11-AUG-07 19:06 9.1
91 NO
c-1234567890-20070812-00 A 12-AUG-07 04:12 0
0 NO
baantest_db_28_1_630961744 A 18-AUG-07 19:09 9.8
88 NO
baantest_db_30_1_630961744 A 18-AUG-07 19:09 10
90 NO
baantest_db_29_1_630961744 A 18-AUG-07 19:09 10
91 NO
c-1234567890-20070819-00 A 19-AUG-07 05:07 0
0 NO
baantest_db_32_1_631566616 A 25-AUG-07 19:10 6.2
88 NO
baantest_db_34_1_631566616 A 25-AUG-07 19:10 6.2
91 NO
baantest_db_33_1_631566616 A 25-AUG-07 19:10 6.3
91 NO
c-1234567890-20070826-00 A 26-AUG-07 01:26 0
0 NO
baantest_db_36_1_632171576 A 01-SEP-07 19:12 9.2
91 NO
baantest_db_37_1_632171576 A 01-SEP-07 19:12 9.1
87 NO
baantest_db_38_1_632171576 A 01-SEP-07 19:12 9.2
91 NO
c-1234567890-20070902-00 A 02-SEP-07 04:27 0
0 NO
baantest_db_40_1_632776372 A 08-SEP-07 19:12 3.5
89 NO
baantest_db_42_1_632776373 A 08-SEP-07 19:12 3.6
91 NO
baantest_db_41_1_632776372 A 08-SEP-07 19:12 3.6
91 NO
c-1234567890-20070908-00 A 08-SEP-07 22:47 0
0 NO
baantest_db_45_1_633380855 A 15-SEP-07 19:07 2.8
11 YES
baantest_db_44_1_633380854 A 15-SEP-07 19:07 2.9
12 YES
baantest_db_46_1_633380855 A 15-SEP-07 19:07 2.9
13 YES
c-1234567890-20070915-00
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Allen, Brandon
Hi Robert, could you please clarify a couple things for me since I've
never tried compressed backupsets?
1) My understanding is that "as compressed backupset" is not recommended
if you're backing up to a tape drive (e.g. LTO3) that is already
performing its own compression. Is that correct?
2) You say compression will save time as well, but I thought that a
compressed backup would actually take longer due to the extra processing
required for the compression.
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