[rescue] reading old unix disks from Linux

Mike Spooner mikes at aalin.co.uk
Fri Apr 26 07:00:43 CDT 2019

Re "Mounting is wierd" - it is possible that partition3 is the correct mountpoint, and the definition of partition1 is just leftover crud (I've seen that with ex-boot disks recycled as data-disks: "let's just format partition3 and use *that*"). That could explain why some files throw errors when partition1 is mounted: the files are valud, but extend outside the boundaries of partition 1. As always, other explanations are possible.

-- Mike

On Fri, Apr 26, 2019 at 10:47 AM +0100, "akb+sites.sunhelp at mirror.to (Andrew K. Bressen)" <> wrote:


I have old SCSI drives I'm trying to read, and I'm running into a number
of different issues I'd welcome feedback on.

I've got drives from PCs, Macs, Suns, and DEC machines, and I'm using a
32 bit linux box (3.x kernel) to read them all. One thing I'm 
wondering is if I'd have fewer problems booting off a FreeBSD or NetBSD

Mostly it's gone well (no sw problems with PC or Mac disks!), but here
are some of the fiddly things I've been dealing with on the DECstation
and Sun disks and would love help/suggestions on. 

Software stack:

Linux often will see a drive as multiple partitions, 
like sdc1 sdc2 sdc3 sdc4, but no linux partion tool
I've found shows me what the boundaries actually are, 
for example parted might say 
  Number  Start  End    Size   File system  Flags
   1      0.00B  105MB  105MB  sun-ufs

on a disk with as many as 7 partitions. 

How do I see what the partitions actually are?


Mounting is weird. 

Often, a disk will have overlapping partitions that will mount.
For example, on one disk, I have 7 partitions. 
Mounting partitions 1 and 3 looks the same at the mount point, 
as do partitions 4 and 7. (3 seems to be the entire disk, 
which is of course normal for old unixes). 

Except with the filesystem mounted via sdc1, some files will throw
i/o errors if I try to read them, but when mounted via sdc3, 
the same files won't. 

Some stuff won't mount. 

So, I have disks of unknown partitions. Some of them are probably swap.
How do I tell? 

Some of them are labeled as SunOS (possibly as old as 3.5) and running
strings on them that looks believable, but they refuse to mount
(error is "wrong fs type, bad option, bad superblock on /dev/loop0,
  missing codepage or helper program, or other error") 
and the ufstype options don't help. What next?

Some stuff is empty. 

In a few cases, I've mounted partitions and seen only a lost+found
directory that's empty. And dated sometime in the 1990s. But if I 
run strings(1) on the dd files of the raw partitions, I see tons
of stuff there. So, am I seeing the remains of deleted files, or
is the UFS driver buggy or having a poor interaction with the kernel's
determination of partitions? Is there an undelete tool for antique UFS?

AND THEN there's hardware questions, but
I'll maybe ask those in a different message...

  --thanks if you've read this far!
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