Db2 – Learning DB2 without a local install

First of all you need to edit/create the /etc/sysctl.conf and insert the following:

 kern.sysv.shmmax=1073741824                                                                                                                                                 
 kern.sysv.shmmin=1
 kern.sysv.shmmni=4096
 kern.sysv.shmseg=32
 kern.sysv.shmall=1179648
 kern.maxfilesperproc=65536
 kern.maxfiles=65536

reboot. Then google db2 express c mac osx and download db2 express c 9.5.2 for mac osx. Once downloaded uncompress the file

tar -xzvf db2exc_952_MAC_x86_64.tar.gz

enter the exp directory and start the installation wizard as root

cd exp
sudo ./db2setup

before continuing you need to create 2 users, one for administration purposes and another one as instance owner. For the second user name use no more than 8 characters and use just letters, otherwise the node name won't be accepted later on. Follow the installation wizard steps: enter the username for the DAS and for the instance owner. Once the installation is complete, you need to switch to the instance owner (dbuser in our case):

su dbuser

add the following line to your .bashrc file:

. ~/sqllib/db2profile

exit and relogin. If everything went well you should be able to start db2 (as a root) and create the SAMPLE database

sudo db2start
db2sampl 
db2

That's it!

As per Information Center:

"If this option is specified when restoring from an online backup image, error SQL2537N will be returned."

So you you are left with rolling forward. That being said, you could try the following

db2 rollforward db mydb to end of backup and complete

According to the information for rollforward command

END OF BACKUP Specifies that all partitions in the partitioned database should be rolled forward to the minimum recovery time. See Examples section below for an example.

This should restore whatever it is you are attempting to restore up to the point of the end of the backup and not include any rolling forward through transactions logs that may be occurring after the backup. Normally you still have to issue at least this statement for a restore from an offline backup where you use archived logs.

I personally haven't tried nor had the need to do an online and only rollforward to the end of the backup. Give it a shot and let us all know what happens.

EDIT: To answer your questions below: You must have archival logging enabled in order to take online backups. You can still take offline backups with archival logging. You do not have to switch back to circular to do so. However, once you have archival logging enabled, regardless of whether you are restoring from an offline or an online backup, you must perform a rollforward when you are done. No way around it. See my own previous question on this.

In order to set up archival logging, you will need to alter the database configuration parameter LOGARCHMETH1. By default, this is set to OFF, which means circular logging. Your choices for it are as follows:

• DISK
• TSM
• USEREXIT
• VENDOR
• LOGRETAIN

LOGRETAIN tells DB2 to leave the archived logs in the logging directory. It will not clean up any of these logs for you (leaving you as the DBA to do so). USEREXIT leaves it up to a non-IBM third party tool to take care of storing and archiving your logs (usually hand coded in C). Not too many people use this anymore from what I understand. DISK and TSM seem to be used a fair amount. DISK tells DB2 where you want to archive your logs off to (although with a few other parameters set, DB2 can automatically clean up logs no longer needed-I'll show you that below). TSM tells DB2 to let IBM's Tivoli Storage Manager to archive off the logs. There are a few other settings you have to get into for that to work. Where I work, we haven't tried that yet. And lastly, VENDOR is used to use a third-party vendor product to archive off your logs.

To set up archival logging of to a different disk spot and have DB2 automatically clean things for you, you can do the following (NOTE:these are in Unix path)

db2 connect to mydb user <admin user> using <admin user password>
#NOTE THE double and single quotes needed on the command line in Unix
db2 "update db cfg using logarchmeth1 'DISK:/dbarch/dblogs'"
db2 update db cfg using num_db_backups 2
db2 update db cfg using rec_his_retentn 2
db2 update db cfg using auto_del_rec_obj on
db2 terminate

This will tell DB2 to keep 2 full backups for at least two full days. Two backups have been kept for two days and another one is taken, the oldest backup will be deleted by DB2. DB2 will also then clean up any logs that were between the now deleted backup and the next oldest retained backup.

Also note: once you switch to archival logging, DB2 will require you to immediately take an offline backup as your next action (ie, the database will be placed into BACKUP PENDING mode) and you will be unable to do anything else until you do so.

Hope this helps!