Bad GPT on 1TB MacBook drive
Posted: 22 Jan 2015, 17:14
My wife's MacBook Pro has a 500GB SSD boot/system disk and 1TB Samsung data disk. As far as I know, the 1TB disk was formatted as a single Mac OS Extended (Journaled) partition using Disk Utility. But something has gone wrong and she now gets an error message on startup that requires her to eject the 1TB disk. Disk Utility will not let me do anything with this disk. I get errors when I try to partition or erase it. (Losing the data is not a huge concern, as her documents are on Google Drive and her music files are available on iTunes Cloud.)
When I ran Analyze and Quick Search on this drive, I got GPT signature missing errors, and then it found 4 partitions. (The drive was at one time the only drive in the MacBook, so it may still have hidden partitions I didn't know about.) Unfortunately, I didn't save the log file from this Quick Search. I started a Deeper Scan about 36 hours ago, and it has only finished about 14% of the drive (270 million of 1.95 billion sectors). At this rate, it will take another week to finish.
So questions for now:
1. This drive uses Advanced Format Technology with, I think, a sector size of 4096. TestDisk reported a sector size of 512, but it reported the correct disk size. Should I use Geometry to set the sector size to 4096, or is this just a difference between physical and logical sector size that TestDisk is recognizing and using correctly?
2. Because of the sector size, or for any other reason, should I stop this deeper scan now and change anything before restarting it? Or perhaps stop and just do a Quick Scan and post the log file now? Or should I let it run for a week and post the log file then?
3. Can my wife use the computer for other tasks while TestDisk is running? If so, any limitations on types of programs or activities?
Thanks in advance. I just don't want to wait another week just to find out I should have done something differently.
Duane
When I ran Analyze and Quick Search on this drive, I got GPT signature missing errors, and then it found 4 partitions. (The drive was at one time the only drive in the MacBook, so it may still have hidden partitions I didn't know about.) Unfortunately, I didn't save the log file from this Quick Search. I started a Deeper Scan about 36 hours ago, and it has only finished about 14% of the drive (270 million of 1.95 billion sectors). At this rate, it will take another week to finish.
So questions for now:
1. This drive uses Advanced Format Technology with, I think, a sector size of 4096. TestDisk reported a sector size of 512, but it reported the correct disk size. Should I use Geometry to set the sector size to 4096, or is this just a difference between physical and logical sector size that TestDisk is recognizing and using correctly?
2. Because of the sector size, or for any other reason, should I stop this deeper scan now and change anything before restarting it? Or perhaps stop and just do a Quick Scan and post the log file now? Or should I let it run for a week and post the log file then?
3. Can my wife use the computer for other tasks while TestDisk is running? If so, any limitations on types of programs or activities?
Thanks in advance. I just don't want to wait another week just to find out I should have done something differently.
Duane