Hall D Work Disk Request

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In recent months we have run out of space on our works disk from time to time. We would like request more space. Clearly more would help right away. Since a bright-line distinction between enough and not enough space is always difficult to make we have estimated how our demand will grow for the next few years.

To estimate the work disk we will need we make the following assumptions:

  1. At CD1 (February 2006) we did not require any disk space at all. CD0 was not used since at that point the project was more speculative that at CD1.
  2. At CD4 (start of operations, June 2015) we will need as much work disk place as Hall B, which is currently 34.5 TB. Note that although at that time Hall D will have no raw data, we will have be doing analyses on Monte Carlo data of a similar volume to that of Hall B analyses. Also note that Hall B is not storing/caching raw data on its work disks and so raw data volume does not affect estimates directly.
  3. We will need to ramp our usage linearly from CD1 time to CD4 time. This is the simplest model.

Work disk estimate.png

The figure shows the projected need with these assumptions. The x-axis is time (the labels indicate the beginning of the calendar year) and the y-axis is disk space in terabytes. According to this estimate we should be at roughly 12 TB of space at this writing (May 2009). Our current allocation is 2.7 TB. We request that this be increased to 5 TB as soon as possible and that increase the total to about 10 TB by the end of the year.