[GLLUG] growisofs -speed=1

[Tim Woodall]

I burn backups to blu-ray about once per month.

Commandline is:
growisofs -dvd-compat -speed=1 -Z /dev/cdrom=$UDFIMAGE

Mostly this works fine: I get messages like:

  2288910336/24756879360 ( 9.2%) @0.9x, remaining 96:21 RBU 100.0% UBU  96.9%
  2302017536/24756879360 ( 9.3%) @0.9x, remaining 96:24 RBU 100.0% UBU  96.9%
  2315321344/24756879360 ( 9.4%) @0.9x, remaining 96:16 RBU 100.0% UBU  96.9%
  2328100864/24756879360 ( 9.4%) @0.9x, remaining 96:10 RBU 100.0% UBU  96.9%
  2340225024/24756879360 ( 9.5%) @0.8x, remaining 96:16 RBU 100.0% UBU  96.9%
  2353135616/24756879360 ( 9.5%) @0.9x, remaining 96:09 RBU 100.0% UBU  96.9%
...

However, it's started burning at double speed @2.1x sometimes. Sometimes
the burn completes like that, but doing an md5sum on the image (which I
always do once I've burned the disk) shows that there are definitely
some errors although the disk will mount ok.

And other times the burn fails part way through.

Does anyone know why it's ignoring my -speed=1 setting?


>From the manpage:
Keep in mind that N essentially denotes speed closest to N*1385KBps in
DVD or N*4496KBps in Blu-ray Disc case

Based on the snippet above - roughly 105 minutes to burn this disk.

24756879360/4496000/0.9 = 101 minutes.

So the maths looks correct and I don't know why it's sometimes burning
at 2.1x.

Tim.