On Thu, 12 Sep 2002, Kablan BOGNINI wrote:

> Hello,
>
> I am using HP DDS-3 tapes for my backup. I've tried to
> get the correct values for my tape. But tapetype gives
> this result:
> define tapetype HP-DDS3-DAT {
>     comment "just produced by tapetype program"
>     length 9860 mbytes
>     filemark 0 kbytes
>     speed 840 kps
> }
>
> I think this is not correct because I've a DDS-3 125M
> tape with 12GB.

Nope, they are not correct. The reason is that you probably have hardware
compression on which actually expands the data Amanda uses to determine
tapesize which in turn gives a smaller length.

However, you are in good company since, even though I have only been on
this list for a short time, this seems to be one of the most frequent
questions here.

I had the same problem and I solved it by removing the drive from it's
drivebox and changing a dip-switch. Some OS:s seems to allows you to
change if the drive should use compression with the mt command (I have not
found it in Solaris 8 though).

Also, tar+gnuzip gives you alot better compression than the internal
hardware of the drive, at least from what I've read on this list.

> Could someone give me more accurate values for this
> tape or point me to doc ?

I use the following tapetype:

define tapetype HP-C1554a {
    comment "just produced by tapetype program"
    length 10075 mbytes
    filemark 0 kbytes
    speed 872 kps
}

Perhaps the length could be a bit larger, but better safe than sorry. If
you change the drive to default to hardware compression off you can rerun
tapetype to get more accurate values.

Hope it helps!

-- 
Conny Gyllendahl

Don't try to have the last word -- you might get it.
                -- Lazarus Long