[GLLUG] growisofs -speed=1

[Tim Woodall]

On Tue, 1 Dec 2020, Tim Woodall via GLLUG wrote:

> 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.
>

And as soon as I sent the above the burn actually failed:

  9682092032/24756879360 (39.1%) @0.9x, remaining 64:22 RBU 100.0% UBU 96.9%
:-( unable to WRITE at LBA=4829a0h: Input/output error
:-( write failed: Input/output error
/dev/cdrom: flushing cache
:-( unable to FLUSH CACHE: Input/output error
:-( unable to SYNCHRONOUS FLUSH CACHE: Input/output error

That's the first time I've had a 0.9 speed burn fail :-(

Tim.