Frequency of backup - daily vs weekly

[paultwang]

Seven files of daily incremental vs. One file of weekly incremental.
Regard file size of the archives, does each use significantly different space than the other?

I leave my computer on 24/7.

[Howard Kaikow]

-{ Quote: "Seven files of daily incremental vs. One file of weekly incremental.
Regard file size of the archives, does each use significantly different space than the other?

I leave my computer on 24/7." }-

A FULL backup backs up all drives you select for backup.
An INCREMENTAL backup backs up only changes to those drives since the prior full/incremental backup of th same drive, so an incremental backup is going to be a lot smaller than a FULL backup.

[bVolk]

I think that seven files of daily incremental will take more space.

New files kept for more than one day (e.g. a photo session), but deleted (moved to CD) before the end of the week, will be included in one of the daily incrementals, but not in the weekly image.

Besides, there must be some overhead to link each incremental file to the previous chain.

[Howard Kaikow]

-{ Quote: "I think that seven files of daily incremental will take more space.

New files kept for more than one day (e.g. a photo session), but deleted (moved to CD) before the end of the week, will be included in one of the daily incrementals, but not in the weekly image.

Besides, there must be some overhead to link each incremental file to the previous chain." }-

Not unless you defrag the drives.
You may be thinking of "differential" backups, which would take more space eventually.

[bVolk]

Hi Howard,

The content and file-size difference between incrementals and differentials is clear, as well as the impact of defragging.

What paultwang asked and what I'm giving my opinion on is, whether a strategy of (smaller) daily incrementals would in the long term need more or less storage space than a strategy of (larger) weekly incrementals.

At least that's how I understand post #1.

[Howard Kaikow]

-{ Quote: "Hi Howard,

The content and file-size difference between incrementals and differentials is clear, as well as the impact of defragging.

What paultwang asked and what I'm giving my opinion on is, whether a strategy of (smaller) daily incrementals would in the long term need more or less storage space than a strategy of (larger) weekly incrementals.

At least that's how I understand post #1." }-

One would have to do a lot of incrementals to come close to the size of a full backup on a typical computer set up.

[paultwang]

-{ Quote: "One would have to do a lot of incrementals to come close to the size of a full backup on a typical computer set up." }-

Size of full backup is not my question. Perhaps an example would be better.

Assume exactly the same hard drive content will appear at any time point.

SCHEME ONE:
Day 1: Full backup created.
Days 2, 3, 4, ... 27, 28, 29: Incrementals created.
Total backup archives size = X bytes.

SCHEME TWO:
Day 1: Full backup created.
Day 8: Incremental created.
Day 15: Incremental created.
Day 22: Incremental created.
Day 29: Incremental created.
Total backup archives size = Y bytes.

Is X significantly larger or smaller, or comparable than Y?

[Howard Kaikow]

-{ Quote: "Size of full backup is not my question. Perhaps an example would be better.

Assume exactly the same hard drive content will appear at any time point.

SCHEME ONE:
Day 1: Full backup created.
Days 2, 3, 4, ... 27, 28, 29: Incrementals created.
Total backup archives size = X bytes.

SCHEME TWO:
Day 1: Full backup created.
Day 8: Incremental created.
Day 15: Incremental created.
Day 22: Incremental created.
Day 29: Incremental created.
Total backup archives size = Y bytes.

Is X significantly larger or smaller, or comparable than Y?" }-


THose are not equivalent operations.

The weeklly incrementals will have only the changes from the previous backups (full and incremental), and will not incluge changes that may be included in the daily incrementals as they may be gone by the time you do the weekly incremental.

The choice should not be based on disk space used, rather the choice should be based on WHAT you wish to back up.

[seekforever]

-{ Quote: "THose are not equivalent operations.
...

The choice should not be based on disk space used, rather the choice should be based on WHAT you wish to back up." }-

A million Amens to that!!!

In other words, don't be penny-wise and pound (dollar, euro) foolish.8)

[thae]

we're doing a full backup every 7 days, and on the other days an incremental one.

the idea of having 1 full backup every month and on all other days incr backups is tempting, but imagine just one of the .tbi becoming corrupt or deleted (can happen, i.e. through hardware error) you'll loose a month worth of data in worst case.

[Howard Kaikow]

The proper solution is to use more than one external drive, let's call them A and B. Then do the following:

27 Mar: Full backup to drive A
28 Mar: Ful backup to drive B
29 Mar: Incremental backup to drive A
30 Mar: Incremental backup to drive B
31 Mar: Incremental backup to drive A
1 Apr: Incremental backup to drive B
.
.
.
At some point, start the cycle over wit Full backups.

I actually use 3 drives, and I alternate between Ghost 10(Always a Full backup using an Independent Recovery Set) and True Image (Full, followed by incrementals).

[bVolk]

I run backups manually and I certainly select the proper time/state to create each of them.

But it seems obvious to me that paultwang is seeking the best of two scheduled strategies. With scheduled backups one cannot exert influence on the contents of each image.

Paultwang's question therefore makes perfectly sense to me and wouldn't be a negligible one in the case of considerable file traffic in/out of harddisk, like photo, video or music editing and compiling.

[paultwang]

-{ Quote: "The proper solution is to use more than one external drive, let's call them A and B. Then do the following:

27 Mar: Full backup to drive A
28 Mar: Ful backup to drive B
29 Mar: Incremental backup to drive A
30 Mar: Incremental backup to drive B
" }-

Manually switch over the external drives? Because I will simply forget.

[Howard Kaikow]

-{ Quote: "Manually switch over the external drives? Because I will simply forget." }-

if you do not use more than 1 drive, you are risking losing all your backups.
disk drives do die.
power problems can wipe out a drive.

the frequency of swapping the drives is a function of the risk you are willing to accept.