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Time Machine backup frequency

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  Time Machine backup frequency Robert Peirce <bob@peirce-family.com> - 2018-06-18 16:44 -0400
    Re: Time Machine backup frequency Jolly Roger <jollyroger@pobox.com> - 2018-06-18 23:07 +0000
    Re: Time Machine backup frequency dempson@actrix.gen.nz (David Empson) - 2018-06-19 12:57 +1200
    Re: Time Machine backup frequency Robert Peirce <bob@peirce-family.com> - 2018-06-19 11:18 -0400
    Re: Time Machine backup frequency Lewis <g.kreme@gmail.com.dontsendmecopies> - 2018-06-20 05:57 +0000

#42959 — Time Machine backup frequency

The docs say this runs once an hour and backs up any files that have 
changed.  That isn't happening on my machine.  I don't know when it 
started but today I noticed I am getting two backups per hour always 
within a couple of minutes.  For example, I have one at 4:08PM and 
another at 4:10PM and that has been the case all day.  Older backups 
seem to conform to the docs.

Clearly this isn't critical.  The older stuff is okay.  However, I am 
curious about what is happening.

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#42960

On 2018-06-18, Robert Peirce <bob@peirce-family.com> wrote:
> The docs say this runs once an hour and backs up any files that have 
> changed.  That isn't happening on my machine.  I don't know when it 
> started but today I noticed I am getting two backups per hour always 
> within a couple of minutes.  For example, I have one at 4:08PM and 
> another at 4:10PM and that has been the case all day.  Older backups 
> seem to conform to the docs.

Where exactly are you seeing these dates?

> Clearly this isn't critical.  The older stuff is okay.  However, I am 
> curious about what is happening.

What does this terminal command show?:

   tmutil destinationinfo

How about this one?:

   tmutil listbackups

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#42961

Robert Peirce <bob@peirce-family.com> wrote:

> The docs say this runs once an hour and backs up any files that have 
> changed.  That isn't happening on my machine.  I don't know when it 
> started but today I noticed I am getting two backups per hour always 
> within a couple of minutes.  For example, I have one at 4:08PM and 
> another at 4:10PM and that has been the case all day.  Older backups 
> seem to conform to the docs.
> 
> Clearly this isn't critical.  The older stuff is okay.  However, I am
> curious about what is happening.

Are you looking at the timeline on the right side of the Enter Time
Machine view? If so, it is probably giving you false clues because it
merges the times of backups done with two separate mechanisms.

Time Machine backs up automatically to external drives once per hour
(assuming the computer is awake, the drive is connected, etc.)

For several OS versions on at least some classes of Mac, Time Machine
also does what it calls "Local snapshots" to the startup volume. These
are done on demand as files change or are deleted, and only if you have
a reasonable amount of free space (plus the system automatically prunes
them if free disk space starts getting low).

Local snapshots don't protect you against drive failure, but they do
allow you to restore files that you accidentally changed or deleted.
(This is completely separate from the "Autosave and Versions" feature.
On HFS+ it involves copying files and is only done for "small" files, on
APFS it uses snapshots of the entire file system.)

The Enter Time Machine view shows both backups and local snapshots on
its timeline. A few OS versions ago they were displayed in different
colours but in recent versions they are indistinguishable.

If you want to see when the backups were done on an external TM drive,
you can open the Backups.backupdb folder on that drive, then open the
folder named for your computer and you will see a folder for each
backup, with the name indicating the date (clearly readable in ISO
year-month-day order) and time (packed HHMMSS).

That list is also produced by this command in Terminal:

  tmtuil listbackups

On High Sierra but not earlier OS versions (at least for APFS volumes,
not sure about HFS+ as I don't have a suitable test machine handy), a
list of local snapshots on the startup volume is obtained with this
command:

  tmutil listlocalsnapshots /

-- 
David Empson
dempson@actrix.gen.nz

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#42962

On 6/18/18 4:44 PM, Robert Peirce wrote:
> The docs say this runs once an hour and backs up any files that have 
> changed.  That isn't happening on my machine.  I don't know when it 
> started but today I noticed I am getting two backups per hour always 
> within a couple of minutes.  For example, I have one at 4:08PM and 
> another at 4:10PM and that has been the case all day.  Older backups 
> seem to conform to the docs.
> 
> Clearly this isn't critical.  The older stuff is okay.  However, I am 
> curious about what is happening.


Looks like they are snapshots.  When I "Enter Time Machine" they all 
show up but a list of backups, or examining the directory itself, 
doesn't show the extra ones while

   tmutil listlocalsnapshots /

does.

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#42964

In message <pg95k0$5c9$1@gioia.aioe.org> Robert Peirce <bob@peirce-family.com> wrote:
> The docs say this runs once an hour and backs up any files that have 
> changed.  That isn't happening on my machine.  I don't know when it 
> started but today I noticed I am getting two backups per hour always 
> within a couple of minutes.  For example, I have one at 4:08PM and 
> another at 4:10PM and that has been the case all day.  Older backups 
> seem to conform to the docs.

What makes you think these are separate backup events instead of a
single backup?

Do you see tow folders in the backup bundle?

-- 
And east is east and west is west and if you take cranberries and stew
them like applesauce they taste much more like prunes than rhubarb does.

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