Hi Tim
Thanks. One more questions I should have asked in my first email:
are we going to scale that for DC1 down to 2%? We would then
be talking about 150 GB, or 600 GB (if we take Kem's estimate),
so serving all this data from a single server would be a viable
option.
Jacek
Tim Axelrod wrote:
Hi Jacek,
Here's a rough calculation. I assume a typical night of 10 hours,
which corresponds to about 1000 observations of distinct fields (sky
positions). For each of those sky positions, we need at the base:
a) Template images for the fields. At roughly 6 GB/image, that gives us
6TB
b) Recent catalog data for all objects in the fields brighter than about
V=25. How much data that is will vary quite a bit, as a previous email
I sent out explains in some detail. For present purposes, I assume
that there are 150000 objects/deg^2 that qualify. I assume that for
each object we need summary information, which I estimate at 200 bytes
(very rough), and the latest 10 epochs of measurements at 50 bytes each.
This then gives us 1000 fields * 150000 * 10sq deg * (200 + 10*50) =
1.5TB. I'd say at present this is no better than a factor of two estimate.
c) calibration images - this is maybe 100GB, negligible.
So a rough guess is 7.5TB.
Cheers,
Tim
Jacek Becla wrote:
Jeff/Tim/Ray
I'd like to start thinking about details of pre-staging
data at the base / partitioning it, but before I do that
I need to understand how much data we are talking about
per night (the question was brought up at today's Database
telecon).
If you could find that out and give me even a rough estimate
whether it is a terabyte or a hundred terabytes, that
would help a lot.
Thanks,
Jacek
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