Joni,

Generally you can look to top or a similar utility to monitor
compression impact on processors during backups.

Compression works by creating a "dictionary" of redundant chunks of
bytes, and replacing repeats of those data chunks in the file with
pointers back to the dictionary.  Dictionary and compressed data are
then saved in the file.  So the more redundant your data, the more
compressed it can be (I had to hand code this once in the early Java days).

We have gone both ways on compression in our client sites.  There are
really three things that make the most difference.

Hardware/OS:  Big processors and lots of memory, little load means
compression has no impact on local performance.  If there is no impact
on the work being done by the client during backup, compression good (I
have seen a Novell server become a swirling vortex of doom when
compression was turned on).

Network:  Small pipe or saturated pipe, compression good.  Big pipe, not
so much.

Data Backed Up:  Sparse data, such a databases, text files, files with
lots of repeating data chunks, compression good.  Lots of images
(compressed formats), compressed archives, encrypted files all have few
repeating data chunks, compression bad.  For example, when we compress
down data we use in our web services (XML format), we get 10 to one--but
there are a lot of repeats (xml tags, and strings).

So, depending on the hardware configuration, network, and data type
compression will cut time.  Outside of the Novell experience, compress
was painless during normal ITSM operation.  You can expect to save
10-50% time on the Oracle box if you have the processor/memory (and you
database is not full of binary data), check if the Lotus files are
compressed or encrypted, that will make a difference.

One test could be to take a representative set of files and gzip them,
and see what you save in size, since that will be similar to what is
sent over the network.

--David Moring
www.backupinsight.com
512-782-HELP

Joni Moyer wrote:

Hello All!

I am considering turning client compression on for our Lotus Notes Domino
and Oracle servers.  What should be looked at/considered before client
compression is turned on?  How do you monitor the impact of turning client
compression on?  Any ideas/suggestions are appreciated!  Thanks!

********************************
Joni Moyer
Highmark
Storage Systems, Storage Mngt Analyst III
Phone Number: (717)302-9966
Fax: (717) 302-9826
joni.moyer AT highmark DOT com
********************************