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Persistent qnx6 filesystem corruption

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Persistent qnx6 filesystem corruption

Postby xl600 » Tue Oct 09, 2018 2:49 pm

I've been fighting this for weeks now, with no resolution. I am attempting to backup whole 6.5.0 systems using tar (pax won't recreate hardlinks properly) and no matter how hard I try, the result is a chkqnx6fs corrupted filesystem report and the inability to mount the filesystem in rw mode.

I've verified no filenames in the archives are > about 150 bytes, yet at the completion of tar extraction, chkqnx6fs reports many (Sometimes thousands) of invalid filename lengths. Invalid inode counts, etc... etc...

I changed the mount to commit=high, which seemed to clear up the vast majority of the errors. But some (Like a few filename length errors) still persist. chkqnx6fs -f does absolutely nothing to help and there doesn't seem to be any way to fix issues other than re-format and try again.

What options are there for diagnosing this and getting to a state where I can properly restore an entire system drive? And how can the so-called Power Safe filesystem even get corrupted like this from extracting a tar file in the first place?

My backup command is:

tar -cpzf $backupfile / -X excludes.txt

Where excludes.txt is:

/proc
/mnt/*
/dev
/fs
/net
/tmp/ssh*
/media

Thanks,

XL600
xl600
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Re: Persistent qnx6 filesystem corruption

Postby Tim » Tue Oct 09, 2018 9:28 pm

xl600,

We probably need a bit more information to help you diagnose this problem.

For example I see your command (tar -cpzf $backupfile / -X excludes.txt) which creates your archive. But you don't say how you are extracting/testing this archive.

What command are you using to extract?
Where are you extracting to? (over top of the existing filesystem you created the tar from, or on a brand new base QNX 6.5 install (ie whatever your base install is)
How big is your tar archive and roughly how many files does it contain?
Have you ever tried extracting elsewhere (say Linux) to see if the archive extracts OK there?
Presumably you are creating an extracting as 'root'?

We use tar here to create software update packages. Our packages are *no where near* the size yours are because they don't contain thousands of files. That said, we've never had a problem restoring a tar archive. We have a much simpler command since everything resides under one directory (no need for excludes).

tar -rvf tarFileName Directory

I am curious about the -z option (filter through gzip) which I've never used. I wonder if that's causing some kind of issue. Also curious why you are extracting the protecting info (p option)?

Tim

P.S. The power safe filesystem is designed to prevent loss of data on power failure. It's won't prevent users or processes from mangling files in some manner.
Tim
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Re: Persistent qnx6 filesystem corruption

Postby maschoen » Tue Oct 09, 2018 11:40 pm

Tim, of course users can mangle files in all sorts of ways but the QNX 6 file system is supposed to prevent file system corruption. If it can do that during a power failure, it should be able to do that without a power failure happening.

There is a requirement for the QNX 6 file system to do its job properly. The underlying hardware must report back correctly when the data has reached the hardware. This hardware that does not do this. This does not explain xi600's problem as he is presumably not losing power.

If I were in this situation I would first try de-archiving onto a QNX 4 file system. If that works it confirms that the tar file is not in doubt. If you have a contract with QNX this would put you into a position to open a ticket. If not, you might try breaking the process up into separate archives for each root directory, and seeing how that works. It might narrow down where the problem is.
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