Re: compressed backup - is this a reasonable size

  • From: "~Jeff~" <jifjif@xxxxxxxxx>
  • To: howard.latham@xxxxxxxxx
  • Date: Fri, 24 Apr 2009 07:53:15 +1200

there's a faster (but less efficient) compression option in 11g so that tape
drives keep streaming. Part of the Advanced Compression option ($$) ...
http://www.oracle.com/technology/products/database/compression/faq.html#I_am_already_using_the_RMAN_backup


2009/4/23 Howard Latham <howard.latham@xxxxxxxxx>

> I had to give up compression as it slows restores so much. At UKOUG last
> year we discussed RMAN best practice - I think it was something Oracle was
> working on.
>
> 2009/4/23 Kenneth Naim <kennaim@xxxxxxxxx>
>
>>  As in all situations it depends; it depends on how many channels are
>> being used, how fast the cpu’s are, what media the backup is going too, how
>> many tape/disk drive are being read from and to, the speed and type of the
>> network between all the points, and the amount of work happening while the
>> backup is running. As a broad generalization slow cpu’s with one or few
>> channels and a fast IO subsystem will result in a slower backup when
>> compression is added or in other words if CPU is the bottleneck in your
>> backup, compression is not recommended.
>>
>>
>>
>> I did an analysis of my clients backup system, where political fingers
>> were being pointed in every direction and each piece of the system was
>> believed to be at fault by a different group. A 6+tb 10gr2 database was
>> being backed up from 150 drive raid 0+1 SAN to a 3 drive tape library system
>> using 24 channels connected via gigabit Ethernet on 12 cpu/24 core Sun 2900.
>> By reviewing the data in the V$BACKUP_SYNC_IO and V$BACKUP_ASYNC_IO views I
>> proved that the bottleneck was on the gigabit network, and that the san was
>> barely being touched. Due to the politics several components were changed
>> simultaneously, the Ethernet to tape was replaced with a single channel 2gb
>> fiber to 160 disk ibm xiv array disk and compression was added. Performance
>> went from 18 hours to under 5. The single fiber card is our new bottleneck
>> and performance should improve once our os team, sun and ibm figure out why
>> the second card is not playing nice.
>>
>>
>>
>> Ken
>>
>>
>>
>> *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
>> oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Tony van Lingen
>> *Sent:* Wednesday, April 22, 2009 9:16 PM
>> *To:* robertgfreeman@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
>> *Subject:* Re: compressed backup - is this a reasonable size
>>
>>
>>
>> That is interesting. I was just discussing this with my collegue who
>> specialises in RMAN backups. He asserts exactly the opposite where it comes
>> to backup times. As an example, we have an GIS database of about 1TB (10g)
>> which backs up in 30 mins in standard mode. When he enables compression it
>> takes up to 6 hours and is very cpu intensive. Apart from that, he agrees
>> that the compression is quite good.
>>
>> Apparently the compression also should not be used in combination with a
>> compressed tape device.
>>
>> Cheers,
>> Tony
>>
>> Robert Freeman wrote:
>>
>> Very reasonable. Compression can do wonders for the size of backup sets!
>> It can also significantly improve overall backup times. What were your times
>> for the backup compressed and non-compressed and how much of a difference in
>> CPU did they make.
>>
>> Be aware that someone on here mentioned a bug with compression just a few
>> days ago.I looked in Metalink for compression related bugs and found a few.
>> In a very quick looksee I find most the bugs seem to be related to backups
>> as opposed to restores. So it seems if you can get a good backup, then you
>> might well be ok. As always, test test test, your restores. No piece of
>> software is perfect! :-) On a regular basis continue to test your restores
>> just in case a bug creeps in. My personal experience with Compression has
>> been very positive.
>>
>> Robert
>>
>>
>>
>> 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:* Jeffrey Beckstrom <JBECKSTROM@xxxxxxxxx> <JBECKSTROM@xxxxxxxxx>
>> *To:* oracle-l-freelists <oracle-l@xxxxxxxxxxxxx><oracle-l@xxxxxxxxxxxxx>;
>> oracle-db-l 
>> <oracle-db-l@xxxxxxxxxxxxxxxxxxxx><oracle-db-l@xxxxxxxxxxxxxxxxxxxx>
>> *Sent:* Wednesday, April 22, 2009 7:36:52 AM
>> *Subject:* compressed backup - is this a reasonable size
>>
>> Just ran the following command.  This is our first RMAN backup.  It backed
>> up a 17G database into about 3G of files.  Is this reasonable?????
>>
>>
>>
>> backup as compressed backupset database plus archivelog delete input;
>>
>>
>>
>> Backup states it finished normally.
>>
>>
>>
>> Jeffrey Beckstrom
>> Database Administrator
>> Greater Cleveland Regional Transit Authority
>> 1240 W. 6th Street
>> Cleveland, Ohio 44113
>>
>
>
>
> --
> Howard A. Latham
>
>
>

Other related posts: