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Time Machine backup size question
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Poobah
Picture of Mary Jo Disler
posted
Does the memory allocation of an external backup drive for Time Machine have to match the amount of drive memory in the computer? Example: Does a 200GB drive machine require a 200GB backup drive or partition?

The TM backups don't appear to take up nearly as much space as the original. I partitioned a 1T external with 321GB for a SuperDuper partition. The rest is devoted to TM, and has been working since Jan.1.

It reads "678.73 GB, 615.15 GB free"
Seems like a lot of free space for that many backups of a 320GB drive.


"For what is age but youth's full bloom,
A riper, more transcendent youth" - Oliver Wendell Holmes
 
Posts: 2074 | Location: West Bloomfield MI USA | Registered: June 13, 2002Reply With QuoteReport This Post
Guru
Picture of Jack Beckman
AIM: Online Status For jcbeckman@mac.com
posted Hide Post
TM backup drive should be TWICE the original, unless you very rarely make changes.

You have to remember Time Machine backs up changes, not a complete system. For example, unless you install patches from Apple, your OS files are not changing day to day. They have only been backed up once on the TM disk. If you have a file you add text to every hour, then that file will be backed up every hour.

Remember too that TM is pruning off old data to make sure it has space. It's going to take those 24 copies of the text file you made and at some point only keep the last one for that day, and eventually get rid of that if you have newer ones and it needs space.

You have less than two months of backups (and it only backs up the space used, not the entire capacity of the drive). How much of the 320 GB drive is actually in use?


===
Professor Hubert Farnsworth: “Nothing is impossible. Not if you can imagine it. That’s what being a scientist is all about.”
Cubert J. Farnsworth: “No, that’s what being a magical elf is all about.”

 
Posts: 5473 | Location: Sterling Heights, Mi | Registered: January 25, 2004Reply With QuoteReport This Post
Poobah
Picture of Mary Jo Disler
posted Hide Post
The 2 partitions show up as 2 volumes. The TM partition reads about as mentioned above:
678.73 GB, 615.17 free

The SuperDuper partition reads:
321 GB, 263.49 GB free.

(These figures are from the desktop icons. I have View Options set to "Show item info.")

The computer drive icon reads:
319.73 GB, 257.46 free (doesn't quite match the SD backup partition, but within the ball park.)


"For what is age but youth's full bloom,
A riper, more transcendent youth" - Oliver Wendell Holmes
 
Posts: 2074 | Location: West Bloomfield MI USA | Registered: June 13, 2002Reply With QuoteReport This Post
Guru
Picture of Jack Beckman
AIM: Online Status For jcbeckman@mac.com
posted Hide Post
You're using 62.27 GB and your TM backup is 63.56, so I'm guessing your changes from day to day since Jan 1 have been minimal.

The reason your SD backup is smaller is that SD doesn't backup temp files and such.


===
Professor Hubert Farnsworth: “Nothing is impossible. Not if you can imagine it. That’s what being a scientist is all about.”
Cubert J. Farnsworth: “No, that’s what being a magical elf is all about.”

 
Posts: 5473 | Location: Sterling Heights, Mi | Registered: January 25, 2004Reply With QuoteReport This Post
Poobah
Picture of Mary Jo Disler
posted Hide Post
Thanks Jack.


"For what is age but youth's full bloom,
A riper, more transcendent youth" - Oliver Wendell Holmes
 
Posts: 2074 | Location: West Bloomfield MI USA | Registered: June 13, 2002Reply With QuoteReport This Post
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