After defragging hard disk, cannot start up.

hey do you think you can help me with my macbook air proble,. basically i downloaded mac os 10.6 and the process it said goto disk utikty well i accidently restored my "Macintosh HD" and turned it into "Mac Os snow leopard dvd install" CD .. so now when it starts up, it goes straight to the CD installation, and not the regular homepage.

Reinstall OS X using your Snow Leopard DVD. Be sure to erase your hard drive before reinstalling.

Drive Preparation

1. Boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu.

2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.

3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID (for Intel Macs) or APM (for PPC Macs) then click on the OK button. Click on the Partition button and wait until the process has completed.

4. Upon completion quit DU and return to the installer. Complete the installation.

+Note: In the future please post your problem in a separate topic rather than hijacking another user's topic. What you did is considered impolite.+

Message was edited by: Kappy

Do the following:

Boot from your external drive. Use Disk Utility to erase your iMac's internal hard drive. Then restore the clone from your external drive.

Clone using Restore Option of Disk Utility

1. Open Disk Utility from the Utilities folder.
2. Select the destination volume from the left side list.
3. Click on the Restore tab in the DU main window.
4.Check the box labeled Erase destination.
5. Select the destination volume from the left side list and drag it to the Destination entry field.
6. Select the source volume from the left side list and drag it to the Source entry field.
7. Double-check you got it right, then click on the Restore button.

Source means the external backup drive.
Destination means the internal startup drive.

For future reference defragmentation is rarely if ever needed. If you must defragment the drive don't use defragging programs. They are potentially dangerous and any glitch can render your drive unbootable as happened to you.

If you must defragment a drive simply clone it to an empty external drive, boot from the external drive, erase the internal drive, restore the clone. This completely defragments the drive, is faster than most defragmentation software, and is far less risky.

Message was edited by: Kappy

I'm sorry, but perhaps I misunderstood. I thought you said you had the internal drive backed up to your external drive. Was I wrong about that?

If I was wrong, then your data on the internal drive may or may not be recoverable. I can suggest the following:

General File Recovery

If you stop using the drive it's possible to recover deleted files that have not been overwritten by using recovery software such as Data Rescue II, File Salvage or TechTool Pro. Each of the preceding come on bootable CDs to enable usage without risk of writing more data to the hard drive.

The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.

Also visit The XLab FAQs and read the FAQ on Data Recovery.

Unfortunately, there's no way at this point to know in what state the drive is.

Old school was simply dump to tape, initialize and restore. Only now you can use CCC or Superduper (probably something in DG3).

Having a bootable clone backup at all times I see as an essential must.

My experience with Drive10 (before TechTool Pro) and other 'defrag' programs (iDefrag?) is they are slow, slower than just restore from your known good clone (because you insured you can boot from it and everything looks and acts fine).

Keep your hard drive to no more than 70% full and if it is a modern hard drive, the performance should be acceptable but when it gets down to 30GB free or below 30% performance does suffer. Some will say 10-15% is where it gets so low it is critical (your directory can't hold all the file and free space fragments properly).

And yes restore with Superduper does clean things up and restore as best as can be, given how full and the drive's specs. You may need to off load files, upgrade to larger drive, or invest in an SSD to get better performance (SSD for OS, 2nd drive for data).

generalstudies™ wrote:
By the way, do you recommend defragmentation of a hard drive or its best to just erase a drive and start over? Will the erase help the hard drive to have a better lifespan?

Neither one is likely to increase the lifespan of a drive. Drives fail more or less proportionally to how much wear & tear they get. Defragmentation utilities work the drive pretty hard since they move so many file segments around in a relatively short period of time, so if anything they are likely to shorten the useable lifespan slightly. A normal (as opposed to secure) erase just erases a few directory files, so it doesn't work the drive hard at all. Restoring from a clone works the drive a fair amount, but since it (mostly) writes whole tracks one at a time in sequence, the write head isn't constantly seeking back & forth, & it isn't as much work for the drive.

But since among other things in normal use the drive is accessing files all over the drive anyway, defragmentation by either method doesn't increase performance all that much to begin with & it should be done infrequently if at all.

I guess the Windows experience really has predisposed many to believe all computers must be maintained like WIndows. Many believe disk defragging a Mac system to be unnecessary. I even believe repairing permissions on Mac disks important before upgrading software. Oh, well.

I've used TIme Capsule for backup purposes. It gives me the ability to restore almost at any level. Carbon Copy cloner is a good app for creating a duplicate of your system disk with the OS and user files intact. After four years if you've loaded up your disk drive you might want to consider upgrading your hard disk; if you're at about 80% of your hard disk limit. I recently replaced my MBP 250GB internal disk with a 750GB disk from OWC for about $135. I now use my old disk as an external portable backup now. OWC offers this as a kit in combination with a new disk purchase.

I don't work for OWC. 😉