Backup performance

System: DB2 8.2 for RedHat Linux (RHEL3) on HP DL380 G3

Runing a full offline backup of a database which produces a backup file of just 200MBytes seems to take a long time. After about 5 minutes 'list utilities' reports the backup as 97% complete. However, the backup takes another 15 minutes to complete.

During this time the filesystem which is the target of the backup file is at around 95% usage (sar -d) with a write speed of about 2MB per second. The tablespaces are on a RAID1 disk pair whilst the backup directory is on a different, RAID1 disk pair. There is almost no disk activity on the tablespace filesystem during this time. All disks are 10K Ultra-320 SCSI, and are connected via single controller.

Simple file copy between the two file systems (either way) has a write speed of around 50MB per second.

Does anyone have any suggestions about what is going on?

Thanks

Martyn Hodgson

In article
<545972418.1136881863788.JavaMail.wassrvr@ltsgwas00 7.sby.ibm.com>,
(martyn.hodgson-at-iipay.com) says...
>
> Does anyone have any suggestions about what is going on?
>

You might have to cleanup your database history file, check the PRUNE
HISTORY command.

hi

What is your , Backup buffer default size (BACKBUFSZ)and how many buffer you are using while taking backup.
Increas this . It will help reduce your time.

vijay singh rathore ( vijaybhai)

I've tried increasing the utility heap size to allow me to increase the backup buffer size and the number of buffers. There is a small improvement (maybe 10%).

However, I've noticed something else. The actual backup file is created within the first 5 minutes of the 20 minute backup and according to the filesystem stats (both the file size, and the last updated date) it isn't updated again. It's as if the backup completes quickly (under 5 minutes) and then DB2 is busy doing something else for the remaining 15 minutes.

In article
<1907073897.1136965554319.JavaMail.wassrvr@ltsgwas0 07.sby.ibm.com>,
(martyn.hodgson-at-iipay.com) says...
> I've tried increasing the utility heap size to allow me to increase
> the backup buffer size and the number of buffers. There is a small
> improvement (maybe 10%).
>
> However, I've noticed something else. The actual backup file is
> created within the first 5 minutes of the 20 minute backup and
> according to the filesystem stats (both the file size, and the last
> updated date) it isn't updated again. It's as if the backup
> completes quickly (under 5 minutes) and then DB2 is busy doing
> something else for the remaining 15 minutes.
>

That's why I said you might need to cleanup your database history.
You can use the PRUNE HISTORY command for that.