Slow Backup

[zap_2]

Hi unix gurus, I have performance issue about Networker 6.1.2.Build.340 Power /10 running on HPUX 11.11 platform.

The problem that I'm currently having slow backup. For example to backup 212 GB it takes about closed to 10 hours at 4.8 MB/s average speed but in good performance in the same backup size it takes about closed to 5 hours at 8.4 MB/s average speed..If this happens, my only solution is restart the server and nsr services and then every thing is ok again.For addition information on my Networker server, only running Networker backup software. I appreciate all of your helps.Thanks in advance.

[Bill Hassell]

Your description is missing important information: Is this a simple system backup on a local tape drive? Or is it over a network connection to another machine with the tape drive? Is the system busy or quiet during the backup period? What type of tape drive are you using?

Modern tape drives are very fast but only when the data reaches the tape faster than needed. When the data slows down, the tape drive completely halts, backs up and restarts the current block of data. This seriously reduces the throughput of the tape drive. Additionally, the backup will appear to run faster if the data is more compressible. Adn of course, if the system is very busy and not much memory is available, it will affect the backup programs.

[R. Allan Hicks]

Interesting question zap.

I had a K460 running Oracle 9i and their complementary legato 7.1 My backup to tape took about an hour.

I upgraded to N servers and just copied the software to the new machines without an install and everything works fine. Oracle runs a lot faster and everyone is really happy except me. My database hasn't changed (much still about the same size) but now it takes about 2.5 hours to back up to tape.

[Stephen Keane]

Remember that backup devices typically use compression. Even if the size of a database doesn't change, if the table contents change, this can affect the compressability of the filespaces when the time comes to back them up. A large, but empty filespace is very compressable.

zap, have you tried running sar or glance whilst the backup is running, it might give you a clue where the bottlenexk is.

Also check you aren't backing up unnecessary filesstems, including NFS mounted filesystems in the backup can have a large performance hit because of the network overhead.

[rick jones]

Did the type of tape device change when you upgraded from th eK to the N? How about the way it is connected to the system?

[R. Allan Hicks]

(Not meaning to poach on zap's question)

Nothing really changed between the K and the N.

The tape drive was integrated in the K server and it's external on the N.

I did a cold backup (fbackup) of the database and then a restore so I guess the files on the new system could be less fragmented.

It just struct me as odd that zap had a 2x increase in his backup time and so did I