Hello everybody,

        if you don't mind, I have two questions concerning hardware compression.

I have two HP Ultrium 960 drives. Up to now I used them with hardware
compression disabled and compressed my data on the clients.

Now I enabled hardware compression and ran amtapetype.

1. The manual says (in Question 12):

"Reasons to run amtapetype for your device:...
- You want to determine if your device has hardware-compression enabled...

and some websites also claim that 'amtapetype' should print a warning
message when HWC is enabled. For some reason, it does NOT on my tape
server. It also reads "hardware compression off" in the final output:

define tapetype LTO3-HWC {
    comment "HP StorageWorks 960 LTO3 (hardware compression off)"
    length 386048 mbytes
    filemark 0 kbytes
    speed 65033 kps
}

I checked HWC several times with standard Unix- as well as with official
HP-software, so that I can say for sure that HWC is now enabled but not
recognized by 'amtapetype'. (I used Amanda 2.5.2p1 and 2.4.5p1)
Should I worry about that?


2. The manual also mentions this:
"When using hardware compression, change the length value based on the
estimated compression rate. This typically means multiplying by
something between 1.5 and 2.0"

So, all I have to do is to run 'amtapetype' with HWC disabled and change
"length 386048 mbytes" -> "length 579072" (something like that)
afterwards. Is this true? Because at

http://wiki.zmanda.com/index.php/Tapetype_definitions#LTO_Ultrium_3_with_400.2F800_Gbyte_tapes

the examples for "HWC on" and "HWC off" are quite identical in length.
So I am a little confused...



Once more, thanks for your help,
        Ralf