Chris
Will someone post the notes from this discussion?
For the record: from database point of view the easiest
would be to serve this data from one database server
(< 8TB is not a lot). Once we understand the load
(number and complexity of the queries) we may be able
to estimate how many CPUs / RAM we would need.
My guess is we should end up with something reasonable
(e.g. "2-4CPU, 16GB RAM"-equivalent in 2012)
thanks,
Jacek
Chris Smith wrote:
Hi all,
Here's the beginning of the thread discussed today on the TechAssess
telecon...
======================================================================== =
Dr. R. Chris Smith EMAIL: [EMAIL PROTECTED]
National Optical Astronomy Observatory
Cerro Tololo Inter-American Observatory
950 N. Cherry Ave. Casilla 603
Tucson, AZ 85719 La Serena, CHILE
Office: 520-318-8555 FAX: 520-318-8170
WWW: http://www.ctio.noao.edu/~chris
======================================================================== =
Begin forwarded message:
From: Tim Axelrod <[EMAIL PROTECTED]>
Date: March 16, 2006 8:10:12 AM MST
To: Jacek Becla <[EMAIL PROTECTED]>
Cc: LSST Data Management <[email protected]>
Subject: [LSST-data] Re: prestaged data - size?
Reply-To: [EMAIL PROTECTED], LSST Data Management <lsst-
[EMAIL PROTECTED]>
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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