Compression - How to Know?

[GregE]

Backing up Oracle LANfree, I have in my dsm.sys:
COMPRESSION ON

I ran this backup LANfree for the first time successfully, but how can I determine that it did not compress the data at the client? (I instead let the tape drive do that)

In my include exclude list for that database I have:
include /DB1/.../full* MC_TAPE
exclude.compression /DB1/.../full*

I have also in my include-exclude list, for logarchives going to disk:
include /DB1/.../log* MC_DISK

How do I know that logarchive backup DOES compress the data?

I don't use the TSM scheduler to backup Oracle. We use a 3rd party enterprise scheduler, so I don't have any information in the dsmsched.log for the backup.

 

[heada]

Compression ON tells the TSM client to compress the data at the client. Compression OFF would NOT compress at the client.

Compression is not enabled/disabled at the filesystem level, only at the client level.

-Aaron

 

[GregE]

But how can I see the compression information? For instance, a regular BA Client scheduled backup has an entry in the dsmsched.log that says:
Objects compressed by: 0%

How can I see this same information for the Oracle backup, to ensure that 1) my full DB backup is uncompressed (as my incl excl file specifies) and that 2) my logarchives ARE compressed, as my incl excl file allows the dsm.sys compression option to let that data compress?

dsm.sys COMPRESSION OFF would have it off, no matter what. COMPRESSION ON turns it on across the board, unless you use exclude.compress to pick which pieces to not compress, as I have done in my inclexcl.

 

[heada]

Look at the stdout for the script. It gives a summary at the end just like you see in dsmsched.log

-Aaron

 

[GregE]

Are you speaking of a generic log that is separate from the one that is written into the script itself? I have our resulting log from the RMAN script. It's detailed as far as creating backup pieces, etc, but nothing along the lines of what dsmsched.log shows, such as amount backed up, compression, etc. But that log creation is custom in the RMAN script, so maybe you're referring to something else that would exist aside from that?

 

[heada]

RMAN should give a summary at the end of the backup that should include the compression factor.

-Aaron

 

[GregE]

Thanks, do you have an example you could post of that and where it would be? I'm looking but can't figure out where to find that.

 

[jnegron]

Can someone explain me how client compression occurs? Does the compression happen in each client drive selected to be backup? Does it cache the new information with in the same drive? If so, is there’s a formula that I can use to calculate the space of cache needed to prevent a drive from filing up.

Thanks