Experimental Physics and
Industrial Control System

On Mar 29, 2007, at 02:04 , Terry Cornall wrote:

I'm trying to dimension the archive requirements for all the 14 beamlines for the Australian Synchrotron and am wondering if I can do it
with one PC or if I need many. Of course, sampling or monitoring rates will play a big part, but also I need to know what is possible per archive engine.

Problem 2:
The amount of data. One 'double' sample uses a little over
20 bytes for the timestamp, status, sev, value.
For many values, the data file structure and index add
relatively little to that, but you'll still get about 20GB
per day. How do you intend to back that up?

If somebody tells you that disks are cheap, please ask
that person to take care of your archiving, then run
as fast as you can.

And besides, with our wide field camera (motor control is
EPICS, array control and data acquisition isn't) that has
4 arrays we get over 50GB per array in a good night with
short integrations. With all 4 arrays we can get well over
a Terabyte in a week.

Yes, it's an archiving problem, but it's entirely doable.
LTO 2 drives in our case generally hold about 300 GB of
compressed data (depends on how compressible your data
are, that's why 'in our case').

Aloha,
Maren

Replies:

Re: Maximum archival rate Greg Lawson

References:

Maximum archival rate Terry Cornall

Re: Maximum archival rate Kay-Uwe Kasemir

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