OK, Here is what I have on AIT-3 tapes. Any tape with under 150 GB was a tape
that was marked prematurely full because of a bug with Networker and NDMP
backups. The data are mostly unix home directories, which may include large
(2 GB) files from Synopsys and Cadence tools. They may be sparse files that
compress easily. I set "limit core 0", so there should be very little from
core files (note that NDMP does not have directives to skip core files).
My past experience with compression is that was way back with DLT IV and
typical compression was 1.7:1 rather than the advertised 2:1.
138 GB full 11/19/04 0 KB 11 50 GB 3501446426 212 8mm AIT-3
333 GB full 11/14/04 0 KB 41 50 GB 713487250 69 8mm AIT-3
56 GB full 06/20/04 0 KB 16 50 GB 3773748481 17 8mm AIT-3
242 GB full 09/26/04 0 KB 30 50 GB 1635024676 9 8mm AIT-3
196 GB full 08/22/04 0 KB 37 50 GB 154394171 24 8mm AIT-3
248 GB full 03/14/04 0 KB 2 100 GB 1604939777 8 8mm AIT-3
314 GB full 11/03/04 0 KB 55 50 GB 3935250322 420 8mm AIT-3
189 GB full 10/19/04 0 KB 27 50 GB 4254008988 110 8mm AIT-3
302 GB full 10/31/04 0 KB 19 50 GB 3029353177 12 8mm AIT-3
386 GB full 09/26/04 0 KB 32 50 GB 1481004563 147 8mm AIT-3
162 GB full 04/04/04 0 KB 2 100 GB 1984741377 24 8mm AIT-3
239 GB full 10/24/04 0 KB 33 50 GB 3046129617 15 8mm AIT-3
149 GB full 07/25/04 0 KB 10 50 GB 3020013536 21 8mm AIT-3
363 GB full 11/07/04 0 KB 20 50 GB 1618247853 126 8mm AIT-3
272 GB full 09/19/04 0 KB 15 50 GB 4266628328 66 8mm AIT-3
375 GB full 10/10/04 0 KB 17 50 GB 1919653867 96 8mm AIT-3
258 GB full 10/03/04 0 KB 11 50 GB 7901980 24 8mm AIT-3
218 GB full 11/07/04 0 KB 20 50 GB 3064118890 18 8mm AIT-3
127 GB full 06/06/04 0 KB 2 100 GB 3464167169 12 8mm AIT-3
237 GB full 08/22/04 0 KB 47 50 GB 3023908132 9 8mm AIT-3
276 GB full 11/07/04 0 KB 12 100 GB 749463133 12 8mm AIT-3
197 GB full 08/08/04 0 KB 11 50 GB 472235738 24 8mm AIT-3
208 GB full 05/09/04 0 KB 3 100 GB 2755659521 33 8mm AIT-3
220 GB full 09/19/04 0 KB 31 100 GB 2035862337 15 8mm AIT-3
272 GB full 11/13/04 0 KB 33 50 GB 145138029 282 8mm AIT-3
241 GB full 04/18/04 0 KB 6 100 GB 1917554689 36 8mm AIT-3
140 GB full 08/22/04 0 KB 12 50 GB 3105982737 71 8mm AIT-3
209 GB full 09/26/04 0 KB 20 100 GB 1969962524 18 8mm AIT-3
80 GB full 08/24/04 0 KB 7 100 GB 3712630897 11 8mm AIT-3
235 GB full 06/13/04 0 KB 32 100 GB 3308771585 36 8mm AIT-3
48 GB full 06/20/04 0 KB 25 100 GB 3929314561 65 8mm AIT-3
124 GB full 06/06/04 0 KB 6 100 GB 3153646337 131 8mm AIT-3
176 GB full 06/29/04 0 KB 16 100 GB 4294138847 15 8mm AIT-3
282 GB full 08/15/04 0 KB 19 100 GB 1728274978 123 8mm AIT-3
139 GB full 04/25/04 0 KB 3 100 GB 2534016769 18 8mm AIT-3
73 GB full 11/19/04 0 KB 14 100 GB 2578783338 122 8mm AIT-3
213 GB full 05/23/04 0 KB 5 100 GB 2998191361 27 8mm AIT-3
97 GB full 06/22/04 0 KB 8 100 GB 3308619265 145 8mm AIT-3
189 GB full 09/12/04 0 KB 36 50 GB 3746183122 24 8mm AIT-3
254 GB full 07/28/04 0 KB 10 100 GB 3122759061 15 8mm AIT-3
227 GB full 08/01/04 0 KB 13 50 GB 505774447 15 8mm AIT-3
317 GB full 11/10/04 0 KB 26 50 GB 2359129550 357 8mm AIT-3
61 GB full 11/12/04 0 KB 12 100 GB 715910549 33 8mm AIT-3
208 GB full 11/14/04 0 KB 18 50 GB 2562007359 5 8mm AIT-3
180 GB full 10/03/04 0 KB 3 100 GB 4286092474 8 8mm AIT-3
114 GB full 10/12/04 0 KB 18 50 GB 3028999736 6 8mm AIT-3
116 GB full 10/12/04 0 KB 8 50 GB 2978677942 11 8mm AIT-3
236 GB full 10/31/04 0 KB 2 100 GB 2962251603 15 8mm AIT-3
125 GB full 10/27/04 0 KB 15 50 GB 127146018 170 8mm AIT-3
153 GB full 11/14/04 0 KB 2 100 GB 732686343 8 8mm AIT-3
196 GB full 11/21/04 0 KB 1 100 GB 4257120418 12 8mm AIT-3
Shelley
On Tue, 25 Nov 2003, Darren Dunham wrote:
> Date: Tue, 25 Nov 2003 08:15:23 -0800
> From: Darren Dunham <ddunham AT TAOS DOT COM>
> Reply-To: Legato NetWorker discussion <NETWORKER AT LISTMAIL.TEMPLE DOT EDU>,
> Darren Dunham <ddunham AT TAOS DOT COM>
> To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> Subject: Re: [Networker] AIT-3 capacity
>
> > Well yes, but I wouldn't call the case of databases, especially if
> > they're backed up by modules specific to the database, a case of
> > compression in the sense that people usually mean it. Databases have
> > much in common with spare matrices where they can be largely empty
> > space. And we see that freqently a database dump is way, way smaller
> > than the database. So the real issue was, I thought, what people
> > could expect under normal circumstances, which would certainly not be
> > anything like 260 gb on a 100 gb tape.
>
> It can still happen, I would just be suspicious of it happening
> constantly. Most of my experience is with 35/70 DLT7000s. My Exchange
> databases were rarely outside the 53-57GB range. Day in, day out, very
> consistent. Portions of the database itself must have been compressed.
>
> Most of our full backups were pretty close to standard, from 60 to 80
> GB, with somewhere around 66-68GB being about normal.
>
> The incrementals were all over the board, but tended to compress more
> than the fulls. I had several 100GB+ tapes. That's more than 2.8:1.
> The average was much closer to 2:1, but I never calculated a real
> average.
>
> Any tape that reported more than 120GB was suspicious and I checked it
> out. I did have some problems a few years ago with some tapes getting
> portions overwritten, so the reported figure was greater than the actual
> figure.
--
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