[Gllug] mount ancient SGI CDs on current Ubuntu

[James Pearson]

Richard Cottrill wrote:
> Hi People,
> 
> I'm messing about with an old SGI Octane I have in my nerd cupboard
> and trying to bring it into the land of the living. Right now I don't
> particularly care what OS it runs, but I have some Irix CDs, and they
> seem like a good start (Linux support for Octane might force me into
> using Gentoo, and life's too short for that).
> 
> Unfortunately, Linux kernel doesn't support the SGI disk labelling
> scheme (man fdisk - could be out of date), but I've found a workaround
> for that ( http://www.geraldthewes.info/pd-2lf-d100onlinux2.6.xhtml ),
> but I can't get it to work.
> 
> I get:
> richard at bletch:~$ fdisk -l -u /dev/scd0
> Note: sector size is 2048 (not 512)
> 
> Disk /dev/scd0 (SGI disk label): 255 heads, 63 sectors, 13 cylinders
> Units = sectors of 1 * 2048 bytes
> 
> ----- partitions -----
> Pt#     Device  Info     Start       End   Sectors  Id  System
>  8: /dev/scd0p1           47776    868935    821160   5  SGI sysv
>  9: /dev/scd0p2               0     47775     47776   0  SGI volhdr
> 11: /dev/scd0p3               0    868959    868960   6  SGI volume
> ----- Bootinfo -----
> Bootfile:
> ----- Directory Entries -----
>  0: sgilabel   sector   32 size     512
>  1: mr         sector   33 size18688000
>  2: sash64     sector36533 size  281656
>  3: sashARCS   sector37084 size  341332
> 
> This suggests to me I need to use an huge offset of (2048 [sector
> size] * 47776 [starting sector of sysv disk partition]) 97845248. So I
> use this unwieldy number thus:
> 
> richard at bletch:~$ sudo losetup -o 97845248 -r /dev/loop0 /dev/scd0
> 
> and now mount:
> 
> richard at bletch:~$ sudo mount -o ro -t sysv /dev/loop0 /mnt
> mount: wrong fs type, bad option, bad superblock on /dev/loop0,
>        missing codepage or helper program, or other error
>        In some cases useful info is found in syslog - try
>        dmesg | tail  or so
> 
> dmesg says something is bust:
> 
> [422121.924000] VFS: unable to find oldfs superblock on device loop0
> 
> Any ideas on how to read this CD?

Older IRIX CDs used SGI's EFS file system - newer ones use XFS

There is support for both file systems in the Linux kernel - although if 
the CD uses 'version 1 directories', then the Linux XFS code won't be 
able to mount the file system: 
<http://oss.sgi.com/projects/xfs/faq.html#useirixxfs>

James Pearson
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