Looking for DiskWarrior Justification

DW has an upgrade to v 3.03 which makes a new disk from the original

If the original disk won't start up the Mac, the updated one won't either. You'll need to pay an upgrade fee for a new disk. Alsoft don't make it as easy as they should to do this. You have to telephone them. When I said I was overseas and their opening hours didn't suit me, they said I could fax in my credit card details.

David Shayer said:

>>>Plus there was an article I read recently from an Apple engineer
>>>say how
>>>with OS X the system will actually do defragging itself in the
>>>background when it thinks the system is quiet enough.
>
>This is true. It's documented here.
>
>http://developer.apple.com/technotes/tn/tn1150.html#HotFile


OS X handles file fragmentation (a file being broken up into bits across
your hard disk) fairly well, but it doesn't handle drive fragmentation
(small spaces between files). In fact, OS X is prone to huge amounts of
drive fragmentation.

Hard drive fragmentation under OS X is mostly irrelevant with respect to
performance. Where hard drive fragmentation becomes important is when
there are no longer any large contiguous free spaces on your drive for OS
X to use for working space, such as for virtual memory, temp files, etc.

When the amount of free contiguous space on your drive starts to become
scarce, OS X can start acting flaky, and eventually, in extreme cases, it
will suffer from data loss.
http://www.macattorney.com/ts.html
see Item #5

I used to recommend that folks defragment their hard drive when it was
approaching 80% full (no matter how large the drive was), because I've
heard from so many folks who were experiencing flaky behavior at this
level (no matter how large their drive was), and defragmenting their
drive invariably fixed the problem. But I've since heard from a number
of users who made heavy use of their drive and they experienced the
problem as early as around 60% full.

So now what I recommend now is that folks check to see how much free
contiguous space there is on their drive occasionally and routinely. You
can do this with the free demo of iDefrag:

http://www.coriolis-systems.com/iDefrag.php

You may never need to defragment your drive (prior to purchasing a new
one) or you may need to do so much earlier than you would expect, but by
checking with this free tool you won't have to guess.

If your drive needs to be defragmented, the *only* hard drive
defragmentation utility that I recommend is iDefrag. It is the only one
that can optimize the files on your hard drive in a totally OS X-savvy
way. OS X now has a journal, a hot band, metadata, etc., it is very
important that these things be located properly or performance will be
compromised. iDefrag is the only hard drive optimization tool that does
this perfectly (despite what some of the other companies, notably
MicroMat, say.)

The downside to iDefrag is that you can't do a comprehensive defrag
without booting from a volume other than the one that you are defragging.
 



Randy B. Singer
Co-Author of: The Macintosh Bible (4th, 5th and 6th editions)

Routine OS X Maintenance and Generic Troubleshooting
http://www.macattorney.com/ts.html

--On April 22, 2006 10:06:42 AM -0700 Nik <gerberinik.net> wrote:

> On Apr 22, 2006, at 12:02 AM, Bill Rowe wrote:
>
>> Given the size of hard drives these days and a modern OS such as OS
>> X, I don't see there is any real need to worry about file
>> fragmentation.
>
> Finally I swapped out the 6GB drive for a 20 GB drive I had laying
> around, and I haven't optimized since. (Thus proving Bill's point.)

It isn't the size of the drive, it's that amount of stuff you keep on them.
Drives with little space free will fragment trying to find places to fit
the the temp file for the application you just opened. Obviously large
drives take longer to fill up, but if tend to keep your drive full then you
may benefit from the occasional defrag (I've defragged once since
installing OS X 10.4 the day it came out.)

-- 

On Apr 23, 2006, at 8:49 PM, patrosh wrote:

> I apologise in advance for asking what may be a silly question...
>
> To defrag a file, is it sufficient to copy it to another hard
> drive? Would
> the file arrive at its new drive complete and fully optimised? One
> could
> then copy that optimised file back to the original drive, and
> replace the
> old fragmented version... YES/NO?

Not a silly question at all. The answer is, well, "maybe."

Assuming there is enough contiguous space on your HD to hold the file
you're copying, the file will not be fragmented when it's copied
over. If there isn't enough space, then the file will be fragmented
after a copy.

--Nik

Can iDefrag be used safely on an Intel Mac with a GUID partition volume?

On Apr 23, 2006, at 10:49 PM, Randy B.Singer wrote:

> If your drive needs to be defragmented, the *only* hard drive
> defragmentation utility that I recommend is iDefrag. It is the
> only one
> that can optimize the files on your hard drive in a totally OS X-savvy
> way. OS X now has a journal, a hot band, metadata, etc., it is very
> important that these things be located properly or performance will be
> compromised. iDefrag is the only hard drive optimization tool that
> does
> this perfectly (despite what some of the other companies, notably
> MicroMat, say.)
>

At 7:49 PM -0700 4/23/06, patrosh wrote:
>I apologise in advance for asking what may be a silly question...
>
>To defrag a file, is it sufficient to copy it to another hard drive? Would
>the file arrive at its new drive complete and fully optimised? One could
>then copy that optimised file back to the original drive, and replace the
>old fragmented version... YES/NO?

If you have a large enough contiguous free block on your disk to hold the file, then the answer is yes.

In fact, it's even simpler than that. Simply duplicate the file on the same disk. HFS+ will try to write the new copy into the contiguous free space, if possible. The delete the old copy, rename the name copy to the old name, and you're done.

Norton Utilities Speed Disk will tell you how large the largest contiguous free block is on your disk. It will also tell you how many fragments a file is broken into.

--

David

Mike Cohen said:

>Can iDefrag be used safely on an Intel Mac with a GUID partition volume?


iDefrag, while compatible with Tiger, isn't yet compatible with
Intel-based Macintoshes. It will be compatible with Intel-based Macs in
version 1.5.

http://www.coriolis-systems.com/iDefrag-faq.php





Randy B. Singer
Co-Author of: The Macintosh Bible (4th, 5th and 6th editions)

Routine OS X Maintenance and Generic Troubleshooting
http://www.macattorney.com/ts.html

Nik said:

>> To defrag a file, is it sufficient to copy it to another hard
>> drive? Would
>> the file arrive at its new drive complete and fully optimised? One
>> could
>> then copy that optimised file back to the original drive, and
>> replace the
>> old fragmented version... YES/NO?
>
>Not a silly question at all. The answer is, well, "maybe."
>
>Assuming there is enough contiguous space on your HD to hold the file
>you're copying, the file will not be fragmented when it's copied
>over. If there isn't enough space, then the file will be fragmented
>after a copy.

Individual files, at least those under 20MB, are already automtically
defragmented by OS X (10.3 or later) when you open them.
http://article.gmane.org/gmane.comp.macosx.general/22906

Back in the days of the classic Mac OS, some users used to defragment
their drive by completely backing it up, erasing the source disk, and
then restoring all of the data from the backup. This both defragments
files, and compacts free space too (disk defragmentation.)

However, as I mentioned previously, under OS X it is important _where_ on
your drive certain files are put. That is, when you defragment your hard
drive under OS X it needs to be optimized in a totally OS X-savvy way for
best performance. So, while backing up your drive and restoring it still
works to defragment your hard drive under OS X, since it isn't a "smart"
defragmentation, it isn't optimal and it may even lead to reduced
performance.



Randy B. Singer
Co-Author of: The Macintosh Bible (4th, 5th and 6th editions)

Routine OS X Maintenance and Generic Troubleshooting
http://www.macattorney.com/ts.html

On 23 Apr 2006, at 20:49 , Randy B. Singer wrote:
> When the amount of free contiguous space on your drive starts to
> become
> scarce, OS X can start acting flaky, and eventually, in extreme
> cases, it
> will suffer from data loss.
> http://www.macattorney.com/ts.html
> see Item #5

See link FROM item #5 to macfixitforums:
>> (1) Clear factual errors. For instance,

[[ ... ]]

>> "[...] If the amount of contiguous free disk space is less than the
>> clump size, and a new piece of Catalog B-Tree or (more
>> likely) Extents B-Tree must be added to the disk, an older
>> piece of Catalog B-Tree or Extents B-Tree is overwritten. [...]"
>>
>> This statement is simply outrageous. It assumes a fundamental
>> error in the design of HFS+ or of Mac OS X which would put to
>> shame a 3rd year comp. sci. undergrad, and which certainly did not
>> exist in HFS. Such an assumption can only be accepted on the basis
>> of strong evidence, and no such evidence is provided.
>>
>> Yet, even granting all these flawed assumptions, the conclusion
>> (that 85% of the disk should be free<1>), still doesn't follow!
>> According to the poster's own logic, on a 100GB volume, this
>> irretrievable damage to the catalogue should occur when there is
>> less than 200MB contiguous space free. That is, 0.2%, not 15%!

<1> He meant 15%

For the record, my 114GB Boot drive has routinely had under 2GB free
space, for months at a time.

The system DOES get wonky when there is very little free space, but
very little means under 100MB, not under 17MB.

--
"Real stupidity beats artificial intelligence every time."

Earlier in this thread, I proclaimed that I would buy Disk Warrior
when I needed it.

I relented over the weekend, and bought a copy. I realized that I
had an "out-of-sight out-of-mind" volume I could test it on. This
was one destroyed volume of three partitions on a firewire drive (I
have been using the other two, but not for anything critical). It
was destroyed when the drive hung during a write operation. Since
the data on the volume was replaceable and Disk Utility was unable to
repair the volume, I had asked Disk Utility to erase the volume--that
operation failed, repeatedly.

Disk Warrior successfully repaired that volume AND produced a
replacement directory which pointed to the surviving valid data from
the broken volume. Seemingly, the HFS+ wrapper had been damaged in
the failure.

For those who saw "Firewire" and "hung during a write" above and know
that I have an iSight: the iSight was not connected at the time of
the failure.

   --John

At 7:49 PM -0700 4/23/06, Randy B. Singer wrote:
>If your drive needs to be defragmented, the *only* hard drive
>defragmentation utility that I recommend is iDefrag. It is the only one
>that can optimize the files on your hard drive in a totally OS X-savvy
>way. OS X now has a journal, a hot band, metadata, etc., it is very
>important that these things be located properly or performance will be
>compromised. iDefrag is the only hard drive optimization tool that does
>this perfectly (despite what some of the other companies, notably
>MicroMat, say.)

I downloaded the demo, and tried to run it.
It asked for an admin password - I declined to provide one.
The app quit.

Opened up the readme file to see what was up.
The readme file said "Use the online help in the application".

Tossed the app into the trash :-(
--
-- Marshall

Marshall Clow Idio Software <mailto:marshallidio.com>

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed,
the hands acquire shaking, the shaking becomes a warning.
It is by caffeine alone I set my mind in motion.

On 4/23/06 at 7:49 PM, patroshhotmail.com (patrosh) wrote:

>To defrag a file, is it sufficient to copy it to another hard drive?
>Would the file arrive at its new drive complete and fully optimised?
>One could then copy that optimised file back to the original drive,
>and replace the old fragmented version... YES/NO?

It depends on the details. If the either of the drives is nearly full to capacity, then doing what you propose is unlikely to achieve any significant defragmentation when only a single file is moved. For example suppose you had a large file fragmented into say several 10MB chunks and had only 5MB free space. Moving the file to the new drive will not cause the free space to become contiguous. So, moving it back will result in no improvement in fragmentation since there will be no contiguous free space large enough to accept the defragmented file.

If both drives have lots of free space, then quite likely the file will be defragmented by doing as you propose. However, if there is lots of free space on the original drive there isn't going to be much problem with file fragmentation in the first place.

If you move *all* of the files from the original drive to a new drive, delete the files from the original drive then move the files back from the new drive to the original drive they will be defragmented.

The old mainframe way to defragment drum memory, and later hard disks, was to copy all the files off to tape, reformat the fixed medium, and copy the files back, which came back on in natural order, unfragmented. Even quite a few "converts" to PCs, in the early days (early 1980s) from mainframe operation, would use a similar routine in the days before effective PC defragmentation: they copied the contents of the hard disk off to a built-in or external tape device, reformatted the HD, and copied the contents back. This is not a good practice today because of the nature of modern operating systems. With the wide-spread use of hard disks on PCs by the mid-1980s, Norton, and others, had developed effective hard-disk defragmentation programs that obviated the need for all that copying. Today's PCs can do defragmenting in the background with the provided utilities or third-party utilities. It has been reported that OSX inherently keeps itself defragmented in ordinary operation.

-- // Bob Perrey // bperrey at sbcglobal dot net // R. Travers Press

I have an iMac G5 2GHz that I have had for 11 months.
I have had it go down on me 5 times Requireing a fresh install of the OS, the last time I could not even mount the rive (Booting from an external Fire Wire Drive).
I Purchased and Downloaded DW, it was able to recover my directory, but reported Hardware problems.
I took my Mac into my local Apple store they ran the basic test on my iMac and said that nothing was wrong, I told them DW had reported a Hard Ware problem. They offered to run a more through diagnostic over night. That diagnostic picked up a Read Write error. They are replacing the HD now.

Regards,
Jeffrey Stephen

Many thanks to all who contributed to the thread on Mac maintenance! And a really big thank you to Randy Singer for his advice both to the forum and to me in private emails.

I downloaded and used apps like MacJanitor and Cache Out X (freewares) and bought iDefrag. After optimising my two hard drives with iDefrag I was stunned by the speed of apps like Photoshop in opening and manipulating files. I now have my old fast G5 back folks!

Paul

At 10:34 AM -0700 4/25/06, Bill Rowe wrote:
>It depends on the details. If the either of the drives is nearly full to capacity, then doing what you propose is unlikely to achieve any significant defragmentation when only a single file is moved. For example suppose you had a large file fragmented into say several 10MB chunks and had only 5MB free space. Moving the file to the new drive will not cause the free space to become contiguous. So, moving it back will result in no improvement in fragmentation since there will be no contiguous free space large enough to accept the defragmented file.
>
>If both drives have lots of free space, then quite likely the file will be defragmented by doing as you propose. However, if there is lots of free space on the original drive there isn't going to be much problem with file fragmentation in the first place.

This is a little confused. It makes no difference whether there is a lot free space on the temporary drive. That is, it makes no difference if the file is fragmented on the temporary drive. It's going to be copied back to the original drive anyway.

>If you move *all* of the files from the original drive to a new drive, delete the files from the original drive then move the files back from the new drive to the original drive they will be defragmented.

This is true. However, OS X may not boot anymore.

--
David

On 5/2/06 at 2:00 PM, tidbitsentience.com (David Shayer) wrote:

>At 10:34 AM -0700 4/25/06, Bill Rowe wrote:

>>If both drives have lots of free space, then quite likely the file
>>will be defragmented by doing as you propose. However, if there is
>>lots of free space on the original drive there isn't going to be much
>>problem with file fragmentation in the first place.

>This is a little confused. It makes no difference whether there is a
>lot free space on the temporary drive. That is, it makes no
>difference if the file is fragmented on the temporary drive. It's
>going to be copied back to the original drive anyway.

Yes, you are right. I could have been clearer in my comments as I am well aware your remarks are accurate.

> >>Plus there was an article I read recently from an Apple engineer
> >>say how with OS X the system will actually do defragging itself
> >>in the background when it thinks the system is quiet enough.
>
> This is true. It's documented here.
>
> http://developer.apple.com/technotes/tn/tn1150.html#HotFile

What that technote describes is, of course, true. However, it
does not describe any capability for OS X to "do defragging in
the background when the system is quiet enough". OS X will
defrag smaller files as it uses them, but it has no background
process that uses idle time for this.

Hey Folks, caught this thread after a google search for 'Invalid Volume Header' and following links;

I see a person asking about iDefrag on MBP - I tried it yesterday - the 1.5 beta version; I think its pretty obvious what happened :|

My fault for not bothering to take a backup - I should know better.. Anyway heads up.. I may be being unfair to iDefrag - I had run the bootcamp program eariler to testdrive winblows on Mac - it failed with a 'not enough contiguous space', which is why I tried iDefrag.. which is why I'm searching the web for a macintel disk volume fixer.. so far I'm down $100 on 'Drive Genius' which isnt MacIntel savvy (doh!), and I'm trying the 'FileSalvage' from SubRosa, I'm not hopeful.. was going to try DiskWarrior but it specifically excludes MacIntel - anyone know if that includes macintel in target mode with diskwarrior on G4?

stupid me, stupid me, arghhhhh,

dave.