Date: Thu, 19 Aug 1999 11:33:43 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Darryl Okahata <darrylo@sr.hp.com> Cc: freebsd-current@freebsd.org, Amancio Hasty <hasty@rah.star-gate.com> Subject: Re: [re]writable cdrom drive Message-ID: <199908191833.LAA57058@apollo.backplane.com> References: <199908191821.LAA08673@mina.sr.hp.com>
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: Another possibility, if you have the RAM, is to use the team(1)
:program (it's in the ports) to buffer the data as it goes to the burner.
:You basically put it into the pipeline between mkisofs and cdrecord, and
:it buffers up to 5MB in memory (default, adjustable). Of course, you've
:got to have enough RAM to not go into swap during the operation. It's a
:very nice program, and I've been told that, with enough memory
:(32-64MB), you can be running X11 and compiling programs while the CD is
:burning (this is with a 2X burner, though).
:
:--
: Darryl Okahata
: darrylo@sr.hp.com
It should be noted that the 'cdrecord' program implements a FIFO itself,
and you can specify the size. The default is 2MB. cdrecord uses a
shared memory segment and forks so the process buffering the data is
made independant of the buffer draining it.
Modern CD writers usually have 1-2MB of buffer internally. The newer
Yamahas, for example, have 2MB.
So right off the bat we have around 4MB. Still, when you are writing at
600KB/sec it is possible to get behind if the filesystem you are building
has lots of small files. Apart from writing the mkisofs output to a file,
the easiest solution is to tell cdrecord to burn at a slower rate - e.g.
1x or 2x instead of 4x or 6x.
-Matt
Matthew Dillon
<dillon@backplane.com>
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