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TOPIC: Partition Repair

Partition Repair 12 Oct 2018 19:25 #10287

Hi!

Few days ago my NAS nested iSCSI HFS+ partition crashed. I don't know what happened, NAS is in perfect health, never had issues before and was running this 10TB partition without any problems.

I tried to repair it with Mojave's built-in Disk Utility which detects some errors and wants to repair if from Recovery. This cannot be done because I can't mount iSCSI partition in Recovery mode. I also can't repair it via Windows PC because it's in HFS+ structure. Obviously...

I ran few recovery apps I have and data seems to be intact. Because It's a large partition and I need large recovery place, I still tend to repair it if possible, rather than going in-to rescue.

... when trying to run repair with TTP 10 I get a message "Repairing the partition map may require reformatting. Male sure all volumes on the device are backed up before proceeding."

What exactly does this mean? Will TTP automatically reformat if it thinks this is needed? Or will it provide options?
Any other advice on this matter is also appreciated. Thank you!
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Partition Repair 12 Oct 2018 19:44 #10288

The warning is the same one that Apple has always given before attempting to write to the partition map. If something goes wrong, and the partition map is made unreadable, all of the volumes on the device will no longer mount.

TechTool Pro does not see NAS volumes. I assume that your quoting of the warning came from looking at a locally attached device.

The beta administrator for TechTool Pro suggested putting the drive in enclosure, such as a USB or FireWire enclosure, which would allow TechTool Pro to see the drive, since it would then be locally attached.

I suggest that once TechTool Pro is able to see the drive, you run the Surface Scan to check it for unremapped bad blocks.
MicroMat Inc
Makers of TechTool
Last Edit: 12 Oct 2018 19:45 by micromattech3.
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Partition Repair 12 Oct 2018 19:52 #10289

I can see my iSCSI partition or "drive" because I can successfully connect to it via iSCSI connector. So in TTP I can see it as an external drive. I can also see it under "Surface scan" as an external drive.

It is a part of RAID array on NAS, which again is fine; no bad blocks or whatsoever. That's why I can't put it in-to an external enclosure.

So, the warning is like a generic one. It does not mean that TTP will reformat partition as part of a recovery process?
I understand that things can go south. I need to understand what TTP will or will not perform.

Thanks.
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Partition Repair 12 Oct 2018 19:59 #10290

Thanks for the clear explanation of how you have made TechTool Pro able to see the drive.

TechTool Pro does not automatically reformat the drive if the repair of the partition map fails. The warning is simply letting you know that if the partition map repair fails, reformatting will be your next step.

Corrupted partition maps are not common, so I still suggest that you run the Surface Scan on the device. A bad block in the partition map could be the cause of the problem. Also, see if the device appears in the SMART test.
MicroMat Inc
Makers of TechTool
Last Edit: 12 Oct 2018 20:02 by micromattech3.
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Partition Repair 14 Oct 2018 01:10 #10293

I clicked the First Aid button in Disk Utility, and was informed that there was corruption on my startup device. I then ran the Partition Map test in TechTool Pro, and the drive passed. Going back to Disk Utility, I got this output:

Checking prerequisites
Checking the partition list
Checking the partition map size
Checking for an EFI system partition
Checking the EFI system partition’s size
Checking the EFI system partition’s file system
Checking the EFI system partition’s folder content
Checking all HFS data partition loader spaces
Checking booter partitions
Checking booter partition disk0s3
Verifying file system.
Checking Journaled HFS Plus volume.
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
The volume Recovery HD appears to be OK.
File system check exit code is 0.
Checking Core Storage Physical Volume partitions
The partition map appears to be OK
Operation successful.

My interpretation is that the operating system performed a minor repair to the partition map after I ran Disk Utility the first time. It was not noted in the system.log file, as it sometimes is during a reboot.
MicroMat Inc
Makers of TechTool
Last Edit: 14 Oct 2018 01:11 by micromattech3.
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Partition Repair 15 Oct 2018 10:12 #10296

Wanted to conclude this topic... TTP was also unsuccessful with partition repair.
So I had to user recovery SW to get data out. Bottom line, due to nature of iSCSI technology I will dismiss it in the future.
Going back to SMB / NFS :)
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Partition Repair 15 Oct 2018 12:47 #10297

Sorry to see you had this outcome, but thanks for the update. At least the hardware is still functioning.
MicroMat Inc
Makers of TechTool
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