Ubuntu 9.04 with file issues Cross posted by intent- we're supposed to compare notes on such problems - I hope.

[Jack]

Jeffrey,

I'm not being dramatic, merely stating the facts. Feel free to point out which of my statements is not factual, and correct me if you find an error in anything I said. Please be specific and quote verifiable sources for your proofs. 

While fsck -y is usually safe or fine if you are getting errors strictly because of a power outage or the system didn't do an orderly shutdown, it is not safe if there is a real hardware issue. It is probably never safe to do on a reiserfs. There are other more obscure filesystems where it isn't safe.

Also, being "fine" is not equal to "no data loss". The original request was to know how to prevent "data loss". Not what was fine. So calling "fsck -y" fine is not even on point and irrelevatnt to the question at hand, and may cause the person asking how to preserve data to lose the very data they are seeking to save. 

Why use it, when there are safer alternatives? You like using it, fine go ahead. But just because you think it's fine and safe, but offer no proof, don't chide me for trying to answer a question seeking detailed knowledge of the fsck command with facts. I believe I've given references for my statements. I've not seen anyone else offer anything other than personal opinions, generic praise of how wonderful the "-y" option is, and slams on my level of paranoia. 

Please feel free to correct me, if I'm wrong. But at least have the courtesy of providing references that can be checked to back up your statements. General references such "for most people..." or "IBM says .." provides no provable or disprovable information. At least a clue where to find the "IBM says ..." reference.

Maybe you should stop being so nonchalent and offer more factual answers. Because, I'm fairtly sure that saying something is fine to run that might cause data loss is not 100% factually correct if one is trying to prevent data loss.

Jack

--- On Sun, 9/5/10, Jeffrey Watts <jeffrey.w.watts at gmail.com> wrote:

From: Jeffrey Watts <jeffrey.w.watts at gmail.com>
Subject: Re: Ubuntu 9.04 with file issues Cross posted by intent- we're supposed to compare notes on such problems - I hope.
To: "Jack" <quiet_celt at yahoo.com>
Cc: "Kclug" <kclug at kclug.org>
Date: Sunday, September 5, 2010, 2:32 PM

Perhaps there's a gem of good information hidden in here, but you've shrouded it in so much dramatic language that I find myself lacking the will to follow up on it.

Seriously Jack, cut out the hyperbole and dramatics.  You're sounding like Chicken Little.  For most people who encounter filesystem corruption, fsck -y is perfectly fine.  Yes, you're right, in certain circumstances it can make things worse.  But then again, in those circumstances a sysadmin would just restore from backup.  If there's no backup and the data is important then I don't think a lay person needs to be messing with it at all - they ought to pay the money to have a pro recover it.


Either way, speak more factually and less dramatically.

Jeffrey.

On Sun, Sep 5, 2010 at 1:34 AM, Jack <quiet_celt at yahoo.com> wrote:


I will continue to disagree with this option, until someone can prove to me that fsck -y is *always* safe to run on ext3 filesystems. When in fact it is known that it can cause further corruption of the filesystem. If the messages are the result of an improper shutdaown, it may be safe, but if the messages are the result of imminent disk failure fsck -y *usuallly* does more damage. Fsck -y is, and was, designed for use by system administrators who know what they are doing. It's not meant to be the lazy man's alternate to safe fs recovery. I'm sorry, I think the response "fsck -y" to a question about wanting to know more about how fsck and the fs work is bad advise at best, and a copout.


Nowhere has the OP said this is the result of an improper shutdown, and he specifically wanted to know how he can find out why he is getting the messages and the safest
 way to fix it. Whether it was safe to have fsck clone the multiply linked files or not, and what the dangers were. To simply say "fsck -y" is an irresponsible response which gives the OP no clues as to what has happened and why.


You said three organizations say it's safe, but provide no proof of that and name only two.  There are numerous people who disagree with you. The simple fact is fsck -y in this particular case *will* result in data loss. While it may be inevitable, it may also make it worse, depending on the cause. We also, don't know if there are still further errors.


However, if my opinion is deemed to be paranoid, and the OP wishes to do the quick and , potentially, easy fix, I would suggest adding a -v to the command so you get a list of the "fixes" in the process., and if you have a alternate disk pipe it to a file as well as the screen. Just know that I am telling you, it can do more damage to the fs and make later
 recovery even worse. Although, apparently, Oracle disagrees with me, and they're ever so trustworthy and probably smarter than me.

Also, make sure you never, ever run fsck -y on a mounted filesystem. Although, maybe, someone here will say that's totally safe too. Now we are also talking here specifically about exzt2/3 filesystems. 


Jack




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