Change which old backups Time Machine keeps

Question

Any body know how to change what older backups Time Machine keeps?  I know how to change how frequently Time Machine backs up (sudo defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int XXXX),
but what I want is for it to not save so many recent backups and keep more of the old ones.  Right now it saves hourly backups for the last 24 hours, daily for the last month, and weekly for each month until you run out of space.  I don't need all the daily stuff, and would really like to keep more of the monthly.  The older the info, the harder it is to recover by other means.  What I'd like to do is keep older backups and lose more of the intermediate ones.
Any ideas?

Answer 1

If you have more than one user account, these instructions must be carried out as an administrator.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Console in the icon grid.
Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left.
Enter the word "Starting" (without the quotes) in the String Matching text field. You should now see log messages with the words "Starting * backup," where * represents any of the words "automatic," "manual," or "standard." Note the timestamp of the last such message. Clear the text field and scroll back in the log to that time. Post the messages timestamped from then until the end of the backup, or the end of the log if that's not clear.
Post the log text, please, not a screenshot. If there are runs of repeated messages, post only one example of each. Don't post many repetitions of the same message.
When posting a log extract, be selective. Don't post more than is requested.
Please do not indiscriminately dump thousands of lines from the log into a message.
Some personal information, such as the names of your files, may be included — edit that out, too, but don’t remove the context.