Mounting ULTRIX CDROMs on Linux

Antonio Carlini a.carlini at
Thu May 20 15:49:52 CDT 2021

On 20/05/2021 21:11, John-Paul Stewart via cctalk wrote:
> Setting ufstype=sun will indeed work for loopback mounting Ultrix CD images.
> With physical CDs, the Linux CD-ROM driver expects the filesystem to use
> 2048 byte blocks but the UFS CDs have 512 byte blocks.  So you'll also
> have to add "loop" to the options:
> sudo mount -t ufs -o ro,ufstype=sun,loop /dev/sr1 /tmp/mount
> That will mount the physical CD using a loopback device so you can
> access the 512 byte per block filesystem.  (FWIW, I learned that trick
> with IRIX EFS CDs, which have the same problem.)

We have a winner:

$ ls /tmp/mount/decw_book/
bookbrowser              d3b0aa70.decw_book d3knaa23.decw_book       
d3s1aa97.decw_book d5e5aaa8.decw_book       dh87zaa1.decw_bookshelf 
BRM410                   d3b0aa71.decw_book d3knaa24.decw_book       
d3s1aaa1.decw_book d5e5aaa9.decw_book       dhqdaa11.decw_book 
BRV410                   d3b0aa72.decw_book d3knaa25.decw_book       
d3s1aaa2.decw_book d5e5zaa2.decw_bookshelf  dhu3aaa3.decw_book 
d296aaa1.decw_book       d3b0aa73.decw_book d3knaa26.decw_book       
d3s1aaa3.decw_book d8dlaaa1.decw_book       dhu3aaa4.decw_book 
d296aaa2.decw_book       d3b0aaa1.decw_book d3knaa27.decw_book       
d3s1aaa4.decw_book d8dlaaa6.decw_book       dhu3zaa2.decw_bookshelf 

Great, thanks for that. I would probably have never guessed that I 
needed loop.


Antonio Carlini
antonio at

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