Re: LTO tape tapesize?

Dave Ewall wrote:

I ran Tapetype on my Ultrium drive (came with a Dell Poweredge server),
and got this:

define tapetype Ultrium {
   comment "Ultrium"
   length 101632 mbytes
   filemark 0 kbytes
   speed 13884 kbytes
}

If I remember right, it took about an hour to run if I gave it the right
parameters.  I played with the parameters for a few days (in spare time)
before I got it right though... otherwise, it was running for daysIt s



It should take about:

   2 passes * (101632 * 1024 kbytes / 13884 kbytes/sec) /pass
        = 14990 sec
  or  about    4 hours 10 min.
 + some time to rewind and stop/start at filemarks.

The stop/start at filemarks is what makes it slower than expected. Themore files it has to write, the slower.

The important parameter is a good guess of the length:

   amtatype -s 100g

would do it fine. The program writes 100 files of 1 Gbyte each. If youlet it the default size estimate of 1Gbyte, then the program will writefiles of 100 Mbyte hoping it will have about 100 when hitting end oftape. But now it needs to write 1000 files. The second pass writesfiles of half the size, and will need to write 2000 files. Now thestart/stop time becomes sigificant in the total runtime, and the programbecomes slow.


Paul

Paul