Simple steps for resolving and diagnosing simple (non) boot issues.
In the past week we have, in the Waitsfield service area, received no less than three machines that after completion of software updates, units that would not restart. The failure in these three machines, one updating to 10.4.11 and two to 10.5.8, was signified by the systems POSTing and starting the boot but failing to progress beyond the gear below the Apple or hanging on a blue screen just after. What is the way to fix when stuck in just this situation.
As discussed several times before, when stuck in this situation we have several steps that can be taken to determine if the failure is software of hardware based,
The first step in fixing the failure to login would be, if your machine reaches the blue screen, the OS Kernel has loaded but the window server and login functions may not be loading properly. To work around this issue, try a safe boot. To start in safe mode, hold the shift key at boot until the gear appears below the Apple and starts to spin, release. Safe boot provides a level of software repair and a paired down system that may provide a stable bootable system. Safe boot information can be found at the following URL,
http://support.apple.com/kb/HT1564
If a Safe boot does not resolve the issue, the next step would be to try more disk repair in single user mode. Single user mode is enacted by staring or restarting the machine holding command key and the letter ‘S’.
http://support.apple.com/kb/HT1492
When finally booted into single User mode, the file system check, fsck command, is another step that could be utilized in fixing the drive.
http://support.apple.com/kb/TS1417
Another single user mode Unix command that could help to determine the reason of the failure would be the command, df -h. From the man page in Terminal regarding df,
The df utility displays statistics about the amount of free disk space on
the specified filesystem or on the filesystem of which file is a part.
Values are displayed in 512-byte per block counts. If neither a file or
a filesystem operand is specified, statistics for all mounted filesystems
are displayed (subject to the -t option below).
The output of the df command would be a readout of how much space your hard drive has and how much space has been used. If your hard drive has reached capacities of 95% or better, your corruption may be a result of too much data on the drive.
If having completed the above steps and your unit will still not start up, you’ll need to probably resort to disk repair using the disk utility while booting from the original media that came with the unit or subsequent install media.
Booted from OSX 10.4 or 10.5 media, in the menu bar to the right of file and edit is an entry, Utilities. Among the Utilities available when booted from OS install media are, Password Reset, Startup Disk, System Profiler, Terminal and Disk Utility. In the drop down, select Disk Utility. In the Disk Utility app, when it loads, select the drive, not the volume, in the left column. In the information provided below, there will be a read out of the SMART status of your drive. SMART is an onboard diagnostic that determines the physical health of your hard drive. If your hard drive is operating nominally the readout of SMART would be verified. After looking at the SMART status of the drive, click the first aid tab and click on repair volume. Much like the fsck, the repair of the drive will be logged in the window and it will list what errors the Disk Utility may encounter. If, having run the Disk Utility and it comes back with no errors repaired, the next step would be to attempt to archive and install the OS. If Disk Utility should find an error and repair, you may attempt to reboot the system to if the repairs fixed the issues that the machine is having.