Hi All,
I'm trying to size TSM servers for some small remote sites that we have. In
the past, with more primitive products, one of the issues has been getting
staff in these locations - generally nurses - to physically change tapes. For
that reason, and to avoid the cost of a library, I'm looking at a disk primary
pool and tape copypool, with db back ups up the wire to a "mother" site.
I've written a program that models the TSM backup and expiry process. Some
assumptions are a small daily update rate, but a file changed yesterday is 50%
likely to be changed today and 25% if it was changed in the last week. I
realize in the real world that there are weekly and monthly cycles too, but
I've left them out for the model for simplicity.
With a 1% daily change rate, 35 day retention and no compression, I'll need 5.7
times the original data space (thats steady state average +3 standard
deviations), but the number is quite sensitive to the daily rate of change
1% 5.7
1.25% 6.5
1.5% 7.1
1.75% 7.9
2% 8.6
2.5% 9.8
3% 10.7
5% 13.2
10% 16.9
At the moment, I don't back up any File servers, so I have no idea what a usual
rate of change might be.
First, can anyone comment on my assumptions.
Second, can anyone share change rates for file servers with a normal load of
office workers creating word processing docs, spreadsheets, etc. I understand
that Netware changes attributes in situations where Windows does not, so if you
could say which type of OS you are using that would be handy too.
Rather than flood the list, email direct to me at steve_harris AT
health.qld.gov DOT au and I'll summarize.
Thanks
Steve Harris
AIX and TSM Admin
Queensland Health,
Brisbane Australia
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