On Mon February 24 2003 13:03, John Oliver wrote:
>On Fri, Feb 21, 2003 at 09:10:35PM -0500, Jon LaBadie wrote:
>> On Fri, Feb 21, 2003 at 03:49:32PM -0800, John Oliver wrote:
>> > On Fri, Feb 21, 2003 at 06:14:37PM -0500, Gene Heskett wrote:
>> > > Throw in that marketing is usually a bit optimistic in
>> > > saying its a 20 gigger without compression, and that always
>> > > needs a fudge factor when actually estimating, and it likely
>> > > this will happen.
>> >
>> > But fudging by 100%? I don't buy that... :-)
>>
>> You don't have to. Gene was only talking about a few percent.
>
>No... if my tape is theoretically capable of 20GB uncompressed and
> 40GB compressed, and after compression amanda can only fit 20GB
> on it, that would hypothetically demonstrate a 10GB un-compressed
> capacity. Or, half of what it's actually doing. I do not
> believe Quantum sells a 10/20 tape drive as a 20/40 I'm sure
> there *is* some fudging going on, but not, like I said, 100%.
> I'm apparently "loosing" about half of the capacity of my tapes,
> and I'm puzzled why I'm the only one who sees a problem with
> that... :-)
>
>Hopefully, this issue will be resolved in a couple of weeks when I
> get a DLT7000 library in here. But I would like to understand
> the basic issue here... I don't want to be limited to 35GB with a
> unit that should be able to approach 70.
John, I thnk we might have a language problem here. When you say
amanda only wrote 20 gigs, how are you determining that? Let me
clip in a couple of lines from last nights run report here to
demonstrate:
--------------------------------
STATISTICS:
Total Full Daily
-------- -------- --------
Estimate Time (hrs:min) 0:23
Run Time (hrs:min) 2:28
Dump Time (hrs:min) 0:58 0:39 0:19
Output Size (meg) 2252.6 2060.9 191.7
Original Size (meg) 4520.0 4004.7 515.3
Avg Compressed Size (%) 49.0 51.5 26.8
(level:#disks ...)
Filesystems Dumped 35 2 33 (1:31 2:1
3:1)
Avg Dump Rate (k/s) 664.2 913.3 169.0
-------------------
The Output size is the actual, written to tape, byte count. In your
case, you appeared to hit EOT at 20 gigs after amanda's
compression. Thats correct. Now note the "Original size" value
and the compression ratio achieved. My tapes are dds2's or a hair
less than 4gigs in real capacity. I have seen, when what it was
backing up was much more compressable than on this particular run,
figures in excess of 10 gigs there a time or 3. I was also running
a dumpcycle one day shorter than now at the time, just to push
amanda to the wall and see what she would do, and IMO she did right
well.
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.23% setiathome rank, not too shabby for a WV hillbilly
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