SUMMARY: scheme to recycle dump tapes

From: Zina Yung (zina@cs.ust.hk)
Date: Fri Mar 31 1995 - 03:35:32 CST


Hello SUN managers:

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My original posting:

Hello SUN managers,

We keep the full image of our file system at the beginning of each
month for as long as we can remember. I wonder how many full dumps
that you keep and what kind of recycling strategy you use in your
site.

Have you heard anything about the exponential decay algorithm?

We'll post a summary. Thanks very much.

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My summary:

Other sites keep their full dump tapes ranging from 6 months to
a years, depending on the type of data. Some important legal data
will never recycled, system files will be kept longer than user files.

I would like to thank every one who responded to my question.
The following are schemes/comments that may be of interest to others:

1. Seven sets of tapes: week1, week2, week3, month1, month2, quarter1,
   and quarter2 ... Depending on your needs you can take a new set
   of tapes each time you arrive to "q2", saving the old one forever.
   Thanks to Alex Pokras <pkrs@isg.co.il>

2. We keep ~12 weeks of daily backups before we start recycling tapes.
   At that point we archive one tape per week (usually monday) and place
   alternate weeks off site.
   Thanks to worsham@aer.com (Robert D. Worsham)

3. we make a back up in the early morning on the 1st day of every month,
   and we keep those tapes for a long long time... (we have never
   recycled these tapes)
   Thanks to Derald.Mcmillan@soltech.com (Derald McMillan)

4. Monthly full dump of system files - kept for 1 year;
   Monthly full dump of user files - kept for 6 months (this was typically
          the first weekly dump of the month)
   Weekly full dump of user files - kept for 6 weeks
   Thanks to "Susan M. Menig" <ddq251f@shoes.Bell-Atl.Com

5. Data tapes 8-mm should be used no more than 35 times
                3M and Basf recommendations.
   Thanks to jcsadmin!jc@eng.dowjones.com (John Ciesla)

7. Legal requirements notwithstanding (we have some Federal customers who
   want everything retained forever) we keep monthly image dumps for three
   years, then recycle
   Thanks to Ross.Stocks.INSDRS01@nt.com

7. I dump every machine completely twice a week on a set of 8 Exabyte
   tapes I use. Then, once a month, I do a monthly dump once a month
   on a set of 6 tapes. Every six months, I make a permanent archive and
   never use it again.
   Thanks to Nico Garcia (raoul@mit.edu)

Zina



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