Hello,
Christoph Harrer <[EMAIL PROTECTED]> wrote:
> I have a Sony SDT-9000 tapedrive, which uses DDS3 (12GB) tapes and should
> operate with a speed of 1.2MB/s, but after a quite long tapetype-run I got
> the following values:
>
> length 9856 mbytes
> filemark 327 kbytes
> speed 961 kbytes
It looks to me like you have hardware compression enabled on the
drive. The tapetype program writes random data to the drive and
attempting to compress random data never works well. In fact,
the "compressed" data will usually be larger than the original.
The speed is slower too, since more tape is required for the data.
You can try running tapetype again with hardware compression disabled.
On some operating systems, that means using a different device name
for the drive, some require using a program like "mt" to set the
compression mode, and in some cases you'll need to set jumpers on
the drive to ensure compression is disabled. Check your man pages
and tape drive manual to find out how to do it for your system.
Once you've run tapetype with compression disabled, you'll probably
get numbers closer to what you're expecting. If you plan to use
software or hardware compression for your amanda dumps then you
can multiply the length parameter by some number between 1 and 2,
depending on how compressible your data is, and put that number in
the tapetype. You should probably err on the conservative side;
1.3 might be a good place to start. You can adjust it later based
upon the actual amount of data that makes it on the tape.
Hope this helps,
-Ben
