Q: 35% Directory Fragmentation

If you feel that defragmentation of the directory would be beneficial, which it most likely would not, all you have to do is erase the volume and restore from a backup. That would be faster and safer than using "Disk Warrior," which is not useful as a maintenance tool.

Contrary to Linc, i use DW, infrequently, to rebuild disk directories. Never had any issue with it. BTW, erasing and restoring a bootable backup/clone isn't not faster than rebuiliding the directory. At least not with my 75 GB boot volume, using CCC.

So these days we don't need be concerned about stuff we used to in the past?

I never was concerned about directory fragmentation, so I'm not sure how to answer that. There are some myths about computer performance that are less prevalent than in the past. "Repairing permissions" is another one.

Is a popular preventive utility like Disc Warrior not needed anymore?

Disk Warrior is an expensive and specialized application whose only use is to try to recover data from a damaged volume that Disk Utility can't repair, and for which there are no backups.

If you're in that position, then instead of spending about $100 on software that you should never need again, make a "Genius" appointment at an Apple Store, where the program is available for the "Geniuses" to use on customers' machines.

The only reason to buy your own copy is that you can't get to an Apple Store, or (like Apple) you provide help-desk services to other Mac users who don't back up their data. Otherwise, Disk Warrior is a complete waste of money. What it does — recreating a volume directory — can be done better and faster for free by erasing the volume and restoring from a backup. That's assuming you have a working backup, of course. Not having one is a mistake you shouldn't make more than once.

The kind of directory corruption that you might need Disk Warrior to recover from can, for all practical purposes, only happen because of a hardware malfunction. It is not caused by forced shutdowns or system crashes. Any drive that malfunctions in that way should preferably be replaced at once. Even if you choose to take the risk of continuing to use the drive after the first such incident, after any repetition the drive should be wiped and recycled, not restored. Occasionally the fault might be in another internal component, or in an external drive enclosure, rather than in the drive mechanism itself.

There may still be some people who believe that rebuilding a volume directory improves performance. There has never been any evidence, as far as I know, to support that belief, and the last time I checked, the developer of Disk Warrior was no longer making such a claim on its website. Whenever I've asked DW enthusiasts to substantiate their belief in its effectiveness, the response has always been along the lines of "Because I say so," or "Because X says so." But every time I check, X either never made the statement, or else he has no data to support it. Nevertheless, if you have reasons of your own to believe that rebuilding a directory is a useful maintenance step — rather than pointless, time-wasting, ignorance-driven busywork — you can do it faster and more safely by erasing the volume and restoring from a backup. No third-party software is needed for that.

Disk Warrior is not a maintenance tool; it's a recovery tool. If you have adequate backups — which means multiple backups — you’ll never need a recovery tool, and therefore Disk Warrior is useless to you. If you don't back up, you'll eventually lose all your data, and Disk Warrior won't be able to save you. Don't waste money on it or anything like it. Spend the money on backup drives instead.

So, I guess I'm OK, right?

No, you're not. Apart from the fact that you're wasting your time with Disk Warrior, you've installed the even more useless "Cocktail" which has been known to cause slowdowns and OS damage. And by not using Time Machine, you risk losing up to 24 hours of work, which is far too much by my standards.

How to maintain a Mac

1. Make redundant backups, keeping at least one off site at all times. One backup is not enough. Don’t back up your backups; all should be made directly from the original data. Don’t rely completely on any single backup method, such as Time Machine. If you get an indication that a backup has failed, don't ignore it.

2. Keep your software up to date. In the App Store or Software Update preference pane (depending on the OS version), you can configure automatic notifications of updates to OS X and other Mac App Store products. Some third-party applications from other sources have a similar feature, if you don’t mind letting them phone home. Otherwise you have to check yourself on a regular basis.

Keeping up to date is especially important for complex software that modifies the operating system, such as device drivers. Before installing any Apple update, you must check that all such modifications that you use are compatible. Incompatibility with third-party software is by far the most common cause of trouble with system updates.

3. Don't install crapware, such as “themes,” "haxies," “add-ons,” “toolbars,” “enhancers," “optimizers,” “accelerators,” "boosters," “extenders,” “cleaners,” "doctors," "tune-ups," “defragmenters,” “firewalls,” "barriers," “guardians,” “defenders,” “protectors,” most “plugins,” commercial "virus scanners,” "disk tools," or "utilities." With very few exceptions, such stuff is useless or worse than useless. Above all, avoid any software that purports to change the look and feel of the user interface.

It's not much of an exaggeration to say that the whole "utility" software industry for the Mac is a fraud on consumers. The most extreme examples are the "CleanMyMac" and “MacKeeper” scams, but there are many others.

As a rule, the only software you should install is that which directly enables you to do the things you use a computer for, and doesn't change the way other software works.

Safari extensions, and perhaps the equivalent for other web browsers, are a partial exception to the above rule. Most are safe, and they're easy to get rid of if they don't work. Some may cause the browser to crash or otherwise malfunction.  Some are malicious. Use with caution, and install only well-known extensions from relatively trustworthy sources, such as the Safari Extensions Gallery.

Never install any third-party software unless you know how to uninstall it. Otherwise you may create problems that are very hard to solve. Do not rely on "utilities" such as "AppCleaner" and the like that purport to remove software.

4. Don't install bad, conflicting, or unnecessary fonts. Whenever you install new fonts, use the validation feature of the built-in Font Book application to make sure the fonts aren't defective and don't conflict with each other or with others that you already have. See the built-in help and this support article for instructions. Deactivate or remove fonts that you don't really need to speed up application launching.

5. Avoid malware. Malware is malicious software that circulates on the Internet. This kind of attack on OS X was once so rare that it was hardly a concern, but malware is now increasingly common, and increasingly dangerous.

There is some built-in protection against downloading malware, but you can’t rely on it — the attackers are always at least one day ahead of the defense. You can’t rely on third-party protection either. What you can rely on is common-sense awareness — not paranoia, which only makes you more vulnerable.

Never install software from an untrustworthy or unknown source. If in doubt, do some research. Any website that prompts you to install a “codec” or “plugin” that comes from the same site, or an unknown site, is untrustworthy. Software with a corporate brand, such as Adobe Flash Player, must come directly from the developer's website. No intermediary is acceptable, and don’t trust links unless you know how to parse them. Any file that is automatically downloaded from the web, without your having requested it, should go straight into the Trash. A web page that tells you that your computer has a “virus,” or that anything else is wrong with it, is a scam.

In OS X 10.7.5 or later, downloaded applications and Installer packages that have not been digitally signed by a developer registered with Apple are blocked from loading by default. The block can be overridden, but think carefully before you do so.

Because of recurring security issues in Java, it’s best to disable it in your web browsers, if it’s installed. Few websites have Java content nowadays, so you won’t be missing much. This action is mandatory if you’re running any version of OS X older than 10.6.8 with the latest Java update. Note: Java has nothing to do with JavaScript, despite the similar names. Don't install Java unless you're sure you need it. Most people don't.

6. Don't fill up your boot volume. A common mistake is adding more and more large files to your home folder until you start to get warnings that you're out of space, which may be followed in short order by a boot failure. This is more prone to happen on the newer Macs that come with an internal SSD instead of the traditional hard drive. The drive can be very nearly full before you become aware of the problem.

While it's not true that you should or must keep any particular percentage of space free, you should monitor your storage use and make sure you're not in immediate danger of using it up. According to Apple documentation, you need at least 9 GB of free space on the startup volume for normal operation.

If storage space is running low, use a tool such as OmniDiskSweeper to explore the volume and find out what's taking up the most space. Move seldom-used large files to secondary storage.

7. Relax, don’t do it. Besides the above, no routine maintenance is necessary or beneficial for the vast majority of users; specifically not “cleaning caches,” “zapping the PRAM,” "resetting the SMC," “rebuilding the directory,” "defragmenting the drive," “running periodic scripts,” “dumping logs,” "deleting temp files," “scanning for viruses,” "purging memory," "checking for bad blocks," "testing the hardware," or “repairing permissions.” Such measures are either completely pointless or are useful only for solving problems, not for prevention.

To use a Mac effectively, you have to free yourself from the Windows mindset that every computer needs regular downtime maintenance such as "defragging" and "registry cleaning." Those concepts do not apply to the Mac platform. A computing device should not be a focus of your attention. It should be an almost invisible tool by means of which you communicate, work, and play. If you want a machine that is always whining for your attention like a neurotic dog, use a PC.

The very height of futility is running an expensive third-party application called “Disk Warrior” when nothing is wrong, or even when something is wrong and you have backups, which you must have. Disk Warrior is a data-salvage tool, not a maintenance tool, and you will never need it if your backups are adequate. Don’t waste money on it or anything like it.

Zapping the PRAM did bring my Mac to normal behavior when it got out of whack

That's not prevention. I didn't say that resetting the PRAM is never necessary. I said it's not necessary for preventive maintenance.

repairing permissions to me is basic maintenance: why would I want to wait till my Mac starts acting up?

Because unless you do something unusual, you'll never have a problem caused by misconfigured system permissions.

I'd be especially interested in reading the story regarding Cocktail

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