OT: Tape backup scheduling: was: Unix stutter

[Bill Vermillion]

On Sun, Sep 12 14:06 , while denying his reply is spam, John Esak 
prattled on endlessly saying: 

> > My take on tape backup is to get it going as fast as possible so it
> > is over as soon as possible.  And if you are doing this at night
> > are there users on the system then?   There shouldn't be, but if
> > there are, can you trust your backups?

> > Bill

> Yes, absolutely there are users at night when the backup is
> done. We are a 24/7 manufacturing facility with multiple
> locations... It has been VERY hard to NOT go down, look for
> redundancy, never be able to safely reshuffle files (without
> lots of preparation), etc. Big hassle, but can I trust my
> backups?? No, of course not, not really. There are files which
> have headers and details separated amongst many files. It
> is altogether possible I might get a mismatch just based on
> that time differential alone, let alone other more typical
> problems.... But, I have to do a complete backup every night
> and simply have to bite the bullet as to the snapshot at the
> time being good enough or close enough should I ever need a
> massive or even selective restore. It's a problem. I do a
> differential during lunch every day... that helps... and a
> monthly... which by the way saved our ass the other day... I
> have four tapes left in the juke box and I want to figure out
> how best to use them to be able to get back to any day. Let me
> tell you how my present system nearly screwed me last week.

That explains that.

Sounds like in the future - when the release gets shaken out and is
solid for a year - you should look at the FreeBSD 5 release.

It has the ability to snapshot a running system and then you backup
the snapshot while work continues, and you backup mirrors the
system at the exact instant of the backup.   Columbia Data products
once did something similar tothis in the MS world with their SnapBack
product.  It made snapshots during those periods when the system
was quiescent.

Now that system are so big and run 24x7 this is something that is
needed.  The snapshot it almost co-mingled with the softudpates
and background fsck on the 5.x series.  It's a rework or rather and
extension of the UFS system which all the FFS systems were based
upon.  It can't get hear soon enough.   

McKusick did most of the work and with his background and the
typical BSD free licensing I expect it will spread to others
soon.



> To all:
> 
> I do the following for backups.
> 
> Master backup
> every night at 11:45pm,  7 tapes
> 
> Differential backup
> every day at 12:30pm,    7 tapes
> 
> Monthly backup
> first day every month at 4:00am,  12 tapes
> 
> This leaves 4 tapes of a 30 tape jukebox.


I have my clients [much smaller] do a similar rotation so that
we can usually get back any file that is less than 30 days old.

Sometimes you don't miss a needed file for awhile and if you rotate
weekly you'll never get it back.

Bill

-- 
Bill Vermillion - bv @ wjv . com