I have a question for you. Does the hardware compression really help
in your setup ?
   Is your network speedy enough to provide sufficient uncompressed
stream in order to keep the drives at their full speed ?
   You have mentioned you have 4 AIT-3 drives. To keep them busy (with
hardware compression on) you should feed each of them with 30-35 MB/s,
which comes to 120-140 MB/s for all of them.
   I remember I tested hardware compression at some point and I found
that it increased our backup timeframe by 50%, just because the data
stream was not sufficient to feed the drives.  So I  switched back to
software (client side) compression.

Craig Ruefenacht wrote:

Hi,

As I stated in my latest post, I was able to get our AIT-3 drives to use
hardware compression with Networker.

The trick was to realize that HP-UX 11.11 doesn't create devices for
compression using the insf command (at least, not by default - maybe
there is someway to do it).

You have to manually create a device with compression enabled for each
AIT-3 drive by using the mksf command (not to be confused with the mkfs
command).  Then you change the devices in Networker to the
compression-enabled devices, and you are off and running.

An aside: the hardware compression on a AIT-3 drive will compress data
for at least AIT-2 and AIT-3 tapes.  We use a mix of both and hardware
compression worked with both types of tapes in the AIT-3 drive.

--
Craig Ruefenacht
UNIX Systems Administrator
USANA Health Sciences
http://www.usana.com

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