Question: Old Irix tape backup. Recovery on Linux (xfsdump/xfsrestore)

[Dave Chinner]

On Thu, Jun 30, 2016 at 12:04:07PM -0500, Eric Sandeen wrote:
> 
> 
> On 6/30/16 11:59 AM, Anthony l wrote:
> > I don't think this is a multi tape dump. But then again i don't know for sure. I recently got a job and this is my first 'project'. I have about 10 tapes each are labeled a month and a year, so I don't think they are multi tape because they span like 3 years 2004-2007 . Although for the current tape I am working on right now if I select 1 skip, I'll get to another back up labeled "incremental backup 1" or something similar. Using the verbosity output here is what I got. (also using interactive restore). I went ahead and specified byte size 4096. Through earlier test using the dd command I determined that was the correct size. Ill post one without byte size specified too. I just saw it in that post and thought it might help.
> > 
> > Here is the output with verbosity.
> > 
> > http://pastebin.com/Nd6BqNc5
> > 
> > The out is the same with or without -b 4096.
> > 
> > http://pastebin.com/0dxbCvyc (no -b)
> 
> 
> interactively restore from this dump?
> 1: skip
> 2: interactively restore
>  (default)
> ->2
> ++++================++++
> missing some stuff------
> 
> ^^^ is that your comment, or actual output?
> 
> Looks like it eventually encountered a short read:
> 
> xfsrestore: drive op: read: wanted 131072 (0x20000)
> xfsrestore: tape op: reading 245760 bytes
> xfsrestore: tape op read of 245760 bytes short: nread == 4096
> xfsrestore: tape op: get status
> xfsrestore: tape status = wprot onl
> xfsrestore: short read record 1 (nread == 4096)
> xfsrestore: drive op read returning error rval=1
> 
> in dmesg, is there any sort of IO error from the tape?

So xfs_reatore is wanting to find the session inventory in that
last media file, and it would appear that it isn't there or shorter
than expected. A tape problem, perhaps? Have you tried running
xfs_restore using the minimal tape protocol (-m)?

Another option is to try to restore the dump files from tape to a
local file on disk and see if that can be parsed instead.

The other thing you might want to do is upgrade xfsdump to the
latest version - you're running 3.1.1 and the current version is
3.1.6. I doubt it will change the behaviour, but at least it will
give us something to work from...

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com