Is Hardware Compression Working??

[Wazzzzzzzzzza]

We are using ArcServe 6.61 Enterprise Edition on an NT Server (SP6) with an Exabyte Mammoth M2 Tape Drive.

By default we enabled "Hardware Compression" (in the Device Manager) for all our backups and until recently we could fit a 70GB backup onto one tape. A sample job log for a successfully completed back would be:

Total Size (Disk) . . . . . . . . . . 69,685.99 MB
Total Size (Media) . . . . . . . . 70,756.18 MB
Elapsed Time . . . . . . . . . . . . 5h 41m 51s
Average Throughput . . . . . .206.95 MB/min

Last week, a second tape was needed to complete the backup. We disabled Hardware Compression and enabled "Software Compression" with the following results:

Total Size (Disk) . . . . . . . . . . 70,852.42 MB
Total Size (Media) . . . . . . . . 49,932.25 MB
Elapsed Time . . . . . . . . . . . . 17h 40m 0s
Average Throughput . . . . . . 66.79 MB/min

Although the backup completed on one tape, at 17 hours, the performance is unacceptably slow!

My questions are:

1. A compression ratio of approximately 30% is achieved via software compression. How can I see what degree of compression is performed when "hardware compression" is enabled.

2. Are these performance figures "common" for Software Compression? Although our ArcServe Server is old (it used to be our SAP server!) it has 4 x Pentium Pro 200Mhz and 4GB of RAM - which should be sufficient.

Thanks

 

[24carat]

Answer to question 1

It is not possible to see Hardware compression ratio figures as far as I know

Answer to question 2

Software compression should not be used at all for the obvious reasons, it is very slow and not that reliable

Tapes are cheap these days so there is no need

Compression also depends on what type of files are being backed up: Text files are the best, Database files the worst

 

[davidmichel]

Compression ratio is a function of the drive, some support it and some don't. If the drive supports it then it will be recorded in the activity log.