October 1, 2004  


Trim That V:Drive

By Shawne Neeper

You probably received the e-mail sent out August 30 with the subject heading: Quotas Now Implemented on Windows Disk Space. It announced new limits on space usage in SLAC’s Windows network drives. Your individual ‘user’ drive, usually mapped as the Z:drive, has an initial limit of 500MB, or six percent greater than your existing usage, whichever is greater. The ‘group’ or V:drive gets the larger of 10GB or 10 percent greater than current usage.

Isn’t Disk Space Cheap?

Disk space is cheaper every year, so many of us have developed the habit of keeping any file that might some day prove useful. It can also seem daunting to comb through many years’ accumulation to sort the needed from the unnecessary. As a result, the use of storage space for personal and group files has doubled every year for the last six years, according to Richard Mount (SCS), associate director for computing services. “Even if you imagine that the current rate of hardware price decreases will continue,” Mount said, “with storage doubling every year, we will be spending the entire SLAC budget on this in 20 years.”

“Another reason [for the quotas],” Mount explained, “is that we have run out of space.” SLAC’s Windows network storage consists of two big boxes containing more than 100 hard drives each, plus about a half-dozen Dell computers that serve the data. There is no more money in this year’s budget to increase that storage space, so SCS devised the quotas to encourage SLAC computer users to delete unnecessary files. “If somebody fills up the disk then a large number of people can’t work,” Mount said. “The quotas are keeping us from disaster.”

Windows Space Request

Take heart. Those who need more space can get it. You will receive e-mail notices as your usage approaches its quota. When you reach 100 percent, you will be able to save any open files, but will need to clear space in order to add files to the server. If you have removed unnecessary files but require more space, fill out the Windows Space Request form on the Web: http://www2.slac.stanford.edu/comp/helptrak/Public/STSubmit2_remedy1.asp?Catg=Windows&CItem=Space%20Request

Windows network storage for SLAC ‘user’ and ‘group’ drives currently requires devices costing a few hundred thousand dollars per year, Mount said. The equipment, and salary for the six employees who maintain this and other network services, are currently funded by indirect cost money—overhead taken from the Lab budget that supports the telephone system, basic site network and e-mail, as well as Windows disk storage.

“While disk usage was small, using Lab overhead money was appropriate,” Mount said. However, as disk usage increases, it will be desirable to fund project-related storage through direct costs—money associated with projects and science. SCS is working on a proposal that will ask SLAC employees to separate project data from files related to individual work, such as letters and CVs—items that would not normally be passed to a job successor.

Under the new proposal, individuals’ files belong on the user’s home directory, the Z:drive, which is expected to use relatively little space. Project work requiring vast amounts of data storage will reside on the group drives. The cost of the large-scale storage would be shared by the divisions using the space. “The beauty [of this approach] is that we get some money to provide space, and avoid having a committee deciding who gets what,” Mount said. “So we begin to tie the really large use of space for science into the projects.” The final definition of the proposal is pending, and will require approval of all SLAC division leaders.




The Stanford Linear Accelerator Center is managed by Stanford University for the US Department of Energy

Last update Wednesday September 29, 2004 by Emily Ball