http://en.wikipedia.org/wiki/Backup_rotation_scheme#Five-Tape_Hanoi_Schedule
On Wed, Mar 24, 2010 at 22:54, Greg Wright <greg.wri...@wineselectors.com.au> wrote: > I have seen (but would have GREAT difficulty replicating) a backup tape > rotation scheme that evenly (give or take a few writes here and there) > utilised 14 (I think it was, maybe 17) tapes over the year, with > specific tapes over the cycle enabling rollback to comprehensive > historical timeframes. > > The result was it was possible to restore previous 5 days along with a > number of weeks, then a number of months ending the year with a yearly > tape. It worked to keep recent backups longer and gradually decreasing > history over longer term and those histories were rotated back into use. > > It did require that during the cycle a few (3 or 4 I think) would get > swapped between themselves to ensure the historical restore options were > there. Ie; One day should have Tape 12 according to the series, but the > tape needed became Tape 5 to reorient the series (I think!) > > I lost the spreadsheet that gave the rotation scheme, and I remember > thinking you would struggle if you missed a particularly important > backup (eg; a monthly) as it might put your scheme out of whack, and > restoring would be a slightly more difficult experience as you would > have to locate and confirm the correct tape number as the sequence was > not 1, 2, 3...7,8 but more like 1,6,3,11,.... > > But in terms of minimising tape numbers and maximising (even) wear it > was pretty impressive. > > Anyone seen anything like that they can explain better than I have? > Anyone up for the maths challenge to come up with it again?!?! > > > -----Original Message----- > From: Ben Scott [mailto:mailvor...@gmail.com] > Sent: Thursday, 25 March 2010 2:07 PM > To: NT System Admin Issues > Subject: Re: NTbackup Methods > > <snip> > > "We do a simple "grandfather/father/son" rotation. Four daily tapes, > MON - THR, which get overwritten weekly. Four Friday tapes, WK2 - > WK5, overwritten monthly. Eleven monthly tapes, JAN - NOV, > overwritten yearly, run on the first Friday of each month. Every year > at the end of December, we run a tape which becomes a permanent > archive, never overwritten. This gives us staggered granularity to > recover from "I just realized I need a file I overwrote last month"." > > <snip> > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ > ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
