Compression of Catalog - Best practice 1

[Tommojunior]

Hi All,

We are running NB4.5-FP6. Our catalog size is approaching 25Gb (and growing organically). We've made some gains in reducing the catalog size by reviewing our policy setups and retention periods but the size is making the creation of the catalog tapes a little painful.

At this time I don't want to restrict the scope of data going to the catalog tape, because any of it could be of use in a DR situation.

Our catalog is already in the default binary format and we have automatic catalog compression set to 21 days.

My question is on the impact (if any) of reducing this time down to say 3 days. Can anyone confirm if:

1) Will there will be any impact to our operator's attempts to perform restores. Is it just a case of master server overhead as NetBackup uncompresses pieces of the database or does it actually stop any restore attempts?
2) We can expect to get a significant reduction in the catalogue size (likely compression ratio?)
3) Is the size of the catalog directly proportional to the time taken to create the catalog tape? and also proportional to the speed of catalog restore in a DR situation.
4) Any other knock-on effects?

All help/guidence/comments most welcome!

Mark

 

[Stumpr]

1) There will be an impact in the time required to search for a file to be restored and it is because of the overhead of the uncompressing of the data files. However, there is a procedure outlined in the sysadmin guide on how to properly uncompress the catalog files for the specific client that you want to search for the restore file. The compression setting does not stop the ability of restores. It only increases the time for selecting the file to be restored.

2) yes, you will see a significant reduction in the catalog size in GB's.

3) yes, the larger the catalog the more time required to copy it and restore it.

4) I suggest limiting the number of days of compression so that you will have one uncompressed full and all of the incrementals for ease of doing restores. Most restore requests will fall into this timeframe. Also there are new catalog backup stategies that you might consider that allows use of a combined NetBackup policy and a catalog dbbackup. Check out the sysadmin guide for details.
5) ENJOY!

Bob Stump
Incorrigible punster -- Do not incorrige

 

[Tommojunior]

Thanks for the advice Bob.

One more piece of guidance if I may.. It's clear from the NetBackup manuals that performing a catalog backup whilst other backups/restores is frowned upon, but what is the real impact?

My limited knowledge of oracle hot/cold backups would lead me to believe that it could have a very bad effect on the ability to restore the catalog.

Having said all that, NetBackup "lets" you do a catalog backup alongside other backups so can it be that bad?!?

 

[creakyjoe]

i have scripts setup to do manual catalog backups; the scripts check that no backups are running before attempting to run, so that the catalog backups are consistent. This is in addition to the 'standard' catalog backups that are set to run after each set of successful backups.

Rich

 

[comtec17]

Netbackup does not allow other backups or restores to process while a Catalog backup is taking place. One item that I perform is to do a flat file backup of the database directory.

 

[Stumpr]

I have experienced no problems with restoring from a catalog that was created whilst active schedules were running. I have seen no trashing of the catalog backup. I have been able to use bprecover at a DR site of a catalog tape that was created by the vaulting option whilst active schedules were running. The only caveat was that the metadata for the then active schedule was not included in the vaulted catalog tape.

Having said all of that, I do try to run the catalog during a quiescent state.

Bob Stump
Incorrigible punster -- Do not incorrige