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TOPIC: Volume Rebuild 17 hours and counting

Volume Rebuild 17 hours and counting 18 Oct 2019 13:45 #11463

I started a Volume Rebuild of my Time Machine drive yesterday. After 17 and a half hours, it's still on the Rebuilding Directory Structures step. Is this normal? Since the Elapsed Time counter is still moving, I'm guessing that the process isn't actually frozen, but this doesn't seem right at all.This is running on an iMac running Mojave with 32GB of RAM, so there should be plenty of memory. Should I quit the process or does a Time Machine volume take much longer to rebuild than a "regular" drive?
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Volume Rebuild 17 hours and counting 18 Oct 2019 14:00 #11464

Generally speaking, we do not recommend rebuilding the disk directory on a Time Machine volume because the disk directory of these volumes is so large. If you have forty backups on your Time Machine volume, and each of the backups has roughly the same number of files, the disk directory is going to be forty times larger than the disk directory of the source volume that has been backed up to the Time Machine volume. There may be only one physical copy of a particular file in the Time Machine volume, but each backup must have its own disk directory entry for that file. The rebuilding process could take days.

Even with 32GB of RAM, you may not be able to rebuild the disk directory of the Time Machine volume, because the new disk directory files, the Catalog B-Tree and the Extents B-Tree, must both be able to be held in RAM simultaneously. Unfortunately, the tools that allow you to see the size of these files no longer work.
MicroMat Inc
Makers of TechTool
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Volume Rebuild 17 hours and counting 18 Oct 2019 14:02 #11465

Then, if TechTool says there is directory corruption, how should I repair it? With Disk Utility?
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Volume Rebuild 17 hours and counting 18 Oct 2019 14:17 #11466

You can try Disk Utility, because it is not replacing the entire disk directory all at once, and is not re-ordering the records to make the Finder a bit more efficient.

I urge you not to have only Time Machine as your backup. Over a period of time, the disk directory tends to get corrupted. In my experience, this is quite likely to happen if you allow Time Machine backups to be made automatically. On the other hand, if you make them manually, for some unknown reason, the Time Machine volume can last nearly two years (again, only my experience). Please see this helpful if impolitely-titled article:

11 Stupid Backup Strategies
MicroMat Inc
Makers of TechTool
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Volume Rebuild 17 hours and counting 18 Oct 2019 14:49 #11469

Thanks for you response. I also have a daily Super Duper! clone backup, but will probably add an offsite backup, too, one day.
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Volume Rebuild 17 hours and counting 18 Oct 2019 14:57 #11470

You are welcome. I think you have a good backup plan, and you will have an even better one when you have an offsite backup.

Dave Nanian, the developer of SuperDuper!, has a blog with a lot of interesting technical information about the challenges of keeping what might appear to be a simple program up to date. He also posts about other things he has learned that might be of interest to his users:

www.shirt-pocket.com/blog/
MicroMat Inc
Makers of TechTool
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Volume Rebuild 17 hours and counting 20 Oct 2019 13:58 #11473

I like Carbon Copy Cloner (there are other utilities that also work in their own fashion like Time Machine). CCC out of Bombich gives me a bootable Mac OS clone of my ... now ... SSD (solid state drive).

Once I got onto to my External SSD (it is a La Cie I terrabyte - a bit bigger then a credit card) sorted out so I could boot up on it ... using TTP to Dx and Repair my internal SSD in the Mac Book Pro was a snap.

Rebuild Desktop was about 22 seconds (as there are some TTP functions that are only allowed by Apple when you are 'Off' the start up drive ... and boot up an external drive such as the TTP electronic drive they have for that purpose .. which I never use as I much prefer a bootable clone to do all my work to save my bacon...

Wow ... really freaking fast.

Downside is that an SSD is vulnerable to a really fast virus destruction ... if you can turn off the Nuke Reactor or Coffee Pot etc by computer .. some one else can turn off that same Nuke Reactor or Coffee Pot etc by another computer elsewhere.

sumbuddie wear blind sea
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