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DiskWarrior - A very useful disk repair tool
Authored by: ciurana on Oct 11, '04 01:07:54PM


I'm a hardcore UNIX guy who returned to the Macintosh fold recently (I stopped coding for Macs in 1992 or so). Can someone please explain what does Disk Warrior do that fsck doesn't?

A friend of mine had a problem with partitions in his Mac (OS X 10.2/LaCie external disk). He used a variety of tools to try to fix it, without much help. I then ran fsck with some command line options for repair and the partition went back to normal; he hasn't had a problem since. I may be missing something but it seems like the OS X file systems can be dealt with in UNIX terms just fine and without having to spend muchos $$$ in software.

Thanks in advance,


San Francisco, CA USA

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DiskWarrior - A very useful disk repair tool
Authored by: boredMDer on Oct 11, '04 01:16:55PM

I'm a UNIX guy as well (well, HP-UX to be exact...), so I know what you mean.

The thing is, most users want to see a nice GUI, pretty widgets that does what they want for them; no need to be 'mucking around' in or such with fsck.

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DiskWarrior - A very useful disk repair tool
Authored by: alani on Oct 11, '04 01:42:35PM

Most users in THIS forum, I'd wager, prefer saving $80 to seeing GUI widgets.

Can you guys describe some of the tricks you would use in FSCK (and feel free to make the obligatory RTFM comment if you must)?

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DiskWarrior - A very useful disk repair tool
Authored by: ahunter on Oct 11, '04 03:37:17PM

If you want to use fsck, then Disk Utility will do that just fine in a graphical manner. The problem is that Apple's fsck does not fix a bunch of problems that can occur with HFS+ (neither does Norton's Disk Doctor, for that matter).

Anyway, here's my story, that should explain why DiskWarrior is a Good Thing:

I was running qmail and leafnode on 10.2: between them, these two programs create and delete a huge number of tiny files. Pretty soon, I started to see lots of kernel panics: one or two a day - this actually looked a lot like bad RAM to me at first, but it eventually became clear that the problem only ever occured when Mail was looking for new mail. Running fsck as single user listed a bunch of problems that fsck said it had decided not to fix (too much effort or something, I guess).

At this point I bought Norton. Disk Doctor improved things: suddenly, the panics were only coming once a week! Woo, at least the people who were still using Windows 98 weren't laughing at me any more. Actually, half the panics now were caused by Norton itself, which insists on installing a couple of dodgy kernel extensions - however, the rest were still happening.

Norton was generally proving a waste of money. Speed Disk didn't work at all (too many directory entries - hooray!) and that undelete thing was basically proving a crash factory, and even after I had spent an hour removing its various tentacles, once a week, Mail was causing a crash. Hrmph.

At this point I ordered DiskWarrior: rebuilding the entire directory sounded a bit drastic and risky to me, but these kernel panics were starting to annoy me. I was sufficiently impatient that I didn't wait for the DiskWarrior CD to be shipped to me (which took 6 weeks to the UK), but built my own very slow boot CD, and (eventually) ran Disk Warrior from there. The directory fragmentation was something like 75% at this point.

So, reboot, half expecting the disk to be totally dead, aaand... Well, it wasn't totally dead. In fact, it felt a bit snappier than before. You might recall that I mentioned leafnode before. The last thing its fetchnews utility does before finishing is 'fork a child process to update XOVER information', something that before I applied DiskWarrior took around 3 minutes - afterwards, it was instantaneous (this always felt wrong, having run leafnode for years on Linux before).

DiskWarrior had recovered one file, too. Unsurprisingly, this was a half-written email that qmail had been processing when I had had a power failure. Evidently, it lurked somewhere in the file system, randomly surfacing to pull yet another hapless kernel into the murky depths of a panic.

Under 10.2, future power failures seemed to cause similar problems fairly regularly. Now I've got 10.3, they happen less frequently, but DiskWarrior still periodically finds things to fix.

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DiskWarrior - A very useful disk repair tool
Authored by: applemandesign on Oct 11, '04 05:31:58PM

so being a unix
how do you get to single user mode w/o using the apple+s keys @ startup?
can you get to it from terminal?

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DiskWarrior - A very useful disk repair tool
Authored by: bryanzak on Oct 11, '04 02:01:37PM

Well, that's like asking what the difference is between KHTML and Gecko.

Sure, both fsck and DiskWarrior do the same thing, but they do it differently. They make different design decision regarding various issues, how aggressive to be, etc.

In my experience, I've had corruption that Disk Utility (which is just a pretty GUI built around fsck) could not fix -- and told me so in nice bold red text. Switch to DiskWarrior and a bit later the drive is once again healthy.


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DiskWarrior - A very useful disk repair tool
Authored by: kupietz on Oct 19, '04 02:18:03PM

Second that. I don't know how or why, but I've had DW fix things after Disk Utility failed.

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DiskWarrior - A very useful disk repair tool
Authored by: Legionary13 on Oct 11, '04 02:02:18PM

From my experience, DW fixes problems that fsck does not. I used to run fsck from console mode periodically, hence the direct comparison. Since Panther, with journalling turned on, fsck reports that it's no longer necessary.

There certainly are utilities that aqua-fy simple command-line tools but DiskWarrior is not one of them. The user manual - cannot find a link on the Alsoft site - explains how DW works, and it is no way comparable with journaling - it's more radical.

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DiskWarrior - A very useful disk repair tool
Authored by: diamondsw on Oct 11, '04 02:12:16PM

The fundamental difference between DiskWarrior and pretty much every other disk utility is how it approaches fixing your problem.

Classic disk utilities (Norton, fsck, etc) work by finding incorrect parts of the directory and patching them with varying degrees of success. DiskWarrior takes a holistic view of the disk and creates a complete new directory from scratch based on all the information it can find (directory bits, other information blocks, etc).

Also aside from a "hand-holding GUI", the other awesome feature of DiskWarrior is it will create a new mountpoint for the fixed drive, effectively laying the new directory over the existing data (write-protected, of course). This allows you to safely examine *exactly* what your drive will look like when it's done, back up items, or anything else you want to do with it. You can also cancel at this point and leave the drive completely untouched - no more "halfway" repairs, as other utilities sometimes stick you with.

I know I've saved at least two dead drives thanks to DiskWarrior.

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DiskWarrior - A very useful disk repair tool
Authored by: leejoramo on Oct 11, '04 04:57:25PM

I have used DiskWarrior for 7 or 8 years. It is often fixed problems when Apple Disk Utility, Norton, TechTools or even single user mode fsck reported the drive as being unsalvageable. What is the difference between fsck and DiskWarrior? I don't really know. As others have said, Apple's Disk Utility is a wrapper around fsck. (And it does a lot of other stuff too.)

I remember reading that the developers of DW use to work for Apple in the development of HFS. They took this deep knowledge of the file system and created a tool that has saved me and my clients many times.

single user mode fsck may fix everything that you ever face. But just remember, that if you ever run into a situation that fsck doesn't do the job, DW will likely be a good investment.

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DiskWarrior - What it does
Authored by: emax on Oct 12, '04 09:24:25AM

DiskWarrior takes a completely different approach to disk repair that fsck/Disk Utility. For a very complete technical explanation and comparison of various disk utilities, check out David Shayer's article in the Nov 24, 03 issue of TidBITS (#707):

He looks at all the major players and objectively describes their strengths and weaknesses. As I recall, DW ends up at the top of the heap.

As for the poster who feels DW fails because it was taking too long to fix his drive, he shouldn't take it out on DW. If a drive is severly damaged, DW can take _significantly_ longer to repair it (as in overnight). But more likely than not, DW will repair the damage. Apparently, the poster needed a working hard drive faster than he needed his data back. Not DW's fault.

Finally, consultants and ad hoc support weenies take note:
DiskWarrior's license specifically states that it's only for use on systems that you own. So if you need to save a client or friend's bacon, that client needs to buy their own license.

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DiskWarrior - What it does
Authored by: rikske on Oct 14, '04 05:39:20PM

In the case of a client, that's just silly. When a client hires me to fix his computer, I need a tool to do the job. So I buy DW. The client doesn't have to buy it. A car mechanic isn't selling his clients tools whenever he fixes their car's isn't he ? That's why the client hires you. Otherwise he can do the job himself too.

But indeed, DW is very good and when I help a friend to fix his computer, I will always recommend to buy it, and usually they do.

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DiskWarrior - A very useful disk repair tool
Authored by: ankh on Oct 18, '04 09:52:47PM

(With journaling, fsck gives false error reports you can ignore.)

I dunno. I've had problems where I did everything else, wasn't getting any error messages, WAS getting unexpected quits and crashes, ran Disk Warrior, it reported fixing problems, rebooted and the problems were indeed gone.

This is how superstitious behavior gets reinforced, I realize. But, somehow, I have gotten to feel like DW can do something the Mac standard tools aren't doing.

Whatever it is. I kind of think it actually creates a new directory, lets you compare it to the old one, and then and only then overwrites the old one. But, I'll leave answering _that_ to experts

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