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TOPIC: Rebuild and Partition Failed

Rebuild and Partition Failed 21 Mar 2019 02:24 #10893

I had an 4TB external drive that I use for Time Machine that stopped getting mounted and was unable to be erased from Disk Utility. I attempted to run Volume Rebuild and Partition Repair but nether got Hard Drive to work. I had to go ahead and use DiskWarrior which solve the issue with a rebuild??
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Rebuild and Partition Failed 21 Mar 2019 02:54 #10894

Most Time Machine volumes have a disk directory that is too large to be held entirely in RAM. TechTool Pro requires that both the Catalog B-Tree and the Extents B-Tree files, which constitute most of the disk directory, be able to be held simultaneously in RAM.

If you have forty backups on your Time Machine volume, then, generally speaking, the disk directory of the Time Machine volume is roughly forty times the size of the relevant source volume. For such a disk directory to be held in RAM, you would have to have far more RAM than most people have.

I suggest you run the Surface Scan on the drive containing the Time Machine volume. The fact that you could not erase the partition with Disk Utility is extremely alarming, a.k.a. a "red flag".

In my experience, the Time Machine volume becomes corrupted relatively soon if you have a lot of files and allow Time Machine to make automatic backups. On the other hand, if you make Time Machine backups manually when not otherwise using your Macintosh, you can get many months of backups.

Time Machine is part of a good backup strategy, but should not be all that you have. Please see this impolitely-titled, slightly out-of-date, and still relevant article:

11 Stupid Backup Strategies.

Some people think they know better than to rely on Time Machine, and instead rely only on a clone backup that does not preserve old versions of files. The problem with such an approach came to my attention when I added some records to my Yojimbo database. After quitting Yojimbo, I used a program to update a clone of my usual startup volume.

I had no way of knowing it at the time, but when I quit Yojimbo and an updated version of my database was written to disk, the new Yojimbo file was corrupted. The new, corrupted Yojimbo database replaced the older, good version in my clone backup. With Time Machine, I was able to restore Yojimbo to the state it was in before I added those few new records. I lost only the few new records, which I could recreate with data still fresh in my head.
MicroMat Inc
Makers of TechTool
Last Edit: 21 Mar 2019 03:16 by micromattech3.
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