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April 10, 2017

3000 backup strategy for closing Sundays

ClosedOnSundayEaster Sunday is on this week's horizon. While it's a rare day of closure at our local HEB grocery chain, Sundays are another sort of closure for 3000 managers. Nearly all of them want their partial backups of the weekdays to wrap up before the backup begins that will serve the work week. If you do full backups every night and want to make the new strategy to do partials during the week and a full on Sunday, there's a way to make that work. Donna Hofmeister, one of the former OpenMPE directors, explained the strategy in a message to 3000 managers.

First you need to decide what kind of partial you want to do.  On Tuesday, do you want to backup all files changed since Sunday's full backup or do you want to backup all files changed since Monday's backup?  (and so on....)

There are some things to think about here. If your "line in the sand" is always Sunday, then you have to deal with knowing that by Friday/Saturday your "partial" backup is likely going to be sizeable and will take longer to run. On the other hand, if you ever have to do a big restore, your restore plan is plan is pretty simple -- you'll need your last partial and your last full backup.

If your "line in the sand" is always yesterday, then your "partial" backups will be relatively small and quick. The flip-side is your big restore could be very complicated, since you'll need every partial backup through Monday plus your full backup. I think most people set the backup date as "Sunday" and do partials from there. But there's a technical bit that's also important.

The bit concerns the command restore ....;date>=!my_lastfull. Donna went on to explain.

"!my_lastfull" is a CI variable that contains a date in "mm/dd/[yy]yy" format.  This is a value that your *full backup job* needs to establish.  So your full backup job should do something like:

         file lastfull,old
         echo !hpmonth/!hpday/!hpyear>*lastful

Your partial job will need to do something like this:

         file lastfull,old
         input my_lastfull < *lastfull

There's plenty of logic that needs to be added to the above examples. (You'll note that there is NO error checking/what-if handling, etc.) This should be enough to get you started.

On incremental vs. differential backups — the former is a backup of changed files since the last full OR partial. The latter is a backup of changed files since the last full.

HP's wisdom about date management for the built-in STORE facility for HP 3000s is in several places. 3K Ranger's Keven Miller volunteered his, and Neil Armstrong's TeamNA Consulting has a downloadable one on file as well.

07:40 PM in Hidden Value, Homesteading | Permalink

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