Network Disk Space at the SSCC

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Last Revised:2/15/2008

This publication is your guide to the some 10 terrabytes of disk space provided by the SSCC. Topics include:

• Key Locations at a Glance
• Windows and Linux
• Private Space
• Project (shared) Space
• Temporary Space
• Backups and Restores
• Managing your Space
• Web Directories

Key Locations at a Glance

Windows and Linux

The SSCC has two parallel file systems: one for Windows and one for Linux. Thus you have two home directories, there are two project directories, etc. A program called Samba makes the Linux file system available to Windows, but not the other way around. This can be a big help to Windows users who are learning Linux, but if you're only using Windows programs, Windows disk space will give better performance.

Private Space

Private disk space is provided in "home directories." In Windows, your home directory is the U: drive. In Linux your home directory is ~, or /home/{first letter of your user name}/{your user name} (e.g. /home/r/rdimond). You can access your Linux home directory from Windows as the Z: drive.

Each home directory starts with 500 megabytes of space. If you need additional space, we will give you an additional 500 megabytes on request. If you still need additional space we will give you an additional 500 megabytes with the approval of your group leader (normally your advisor or supervisor). This means you can have a total of three gigabytes of space in your Windows and Linux home directories combined. If you need more than this, consider requesting a project directory. You can request additional space in your home directory by filling out a web form. To check how much space you're using, in Windows right-click on your U: drive and choose Properties; in Linux type quota.

Home directories are private: other SSCC users cannot access files in your home directory.

Project Space

Project space is mainly for groups working together on a common project, though if you need more space than can be provided in your home directory it's possible to request a project directory for one person. Project directories can be as large as needed, but keep in mind that disk space is costly (see Managing your Space).

Windows project folders can be found on the X: drive. Linux project directories can be found under /project. Linux project directories are available from Windows on the V: drive.

Each project directory has an associated group of users who can access the directory. Other users cannot. If you need access to a particular project directory, the owner of that directory must contact the SSCC consultant and ask that you be added to the group.

If you'd like to request a project directory, the easiest way is to send the consultant an email with the following information:

• The name of the desired directory
• Whether it should be created in Windows or Linux
• A list of people who should have access to the directory

Normally project directories should be created in the same operating system (Windows or Linux) as the programs you'll be using. However, if you'll be using both Windows and Linux programs the directory should be created in Linux.

Temporary Space

Both Windows and Linux have space where you can store files temporarily, however they are quite different.

In Windows, temporary space is available on the Y: (Public) drive. The Y: drive is completely public: any SSCC user can read, change, or delete any file on the Y: drive. This makes it a convenient place for sharing files with others, however, it should never be used for confidential data (or for any serious research data, really). Any files on the Y: drive which have not been used for 30 days will be deleted automatically.

In Linux, temporary space is available in /temp/fivedays. If you wish to use it, create a subdirectory for your files (e.g. /temp/fivedays/rdimond). Directories under /temp/fivedays can be public or private depending on the permissions you set--by default they are private. However, any files in /temp/fivedays will be deleted after five days (as suggested by the name).

If you need to access the Linux temporary space from Windows, you'll need to map a drive to it.

Note that temporary space is not backed up in either Linux or Windows. Temporary space is not intended for long-term storage of important files.

Backups and Restores

Home and project directories, system directories such as web sites, and email are backed up onto tape every night. These tapes are stored for a year. See the SSCC Data Integrity Policy for details. This means that if anything goes wrong with a file, we can restore it to how it was the night before, or any other night in the last year. However, if the file has not been on disk overnight (e.g. a file you created this morning) it has not been backed up and cannot be restored. Also, files on local hard drives (C: or D:) are not backed up. We hate to see anyone lose data, so please store all important files on the network where they are backed up. We also suggest that you keep your own backup copies of important files on CD or DVD--you can make them in the SSCC computer labs in 3218 and 4218.

If you need a file restored, send send the consultant an email with the following information:

• The operating system the file was stored on (Windows or Linux)
• The name of the file
• The full location of the file (e.g. U:\dissertation\absolutely critical data or ~/dissertaion/absolutelyCriticalData)
• The date as of which you want it recovered (e.g. "last night's backup")

If the file has been deleted and you don't know some of this information, just do your best and we can usually find it.

Please keep in mind that restoring files from tape takes a signficant amount of staff time. Older backups are stored off-site and there will be additional delays if we have to order the relevant tape.

Managing your Space

The SSCC uses Storage Attached Network (SAN) devices to provide disk storage that is extremely fast and reliable. However, this storage space is much more expensive than a regular PC hard drive--in fact disk space is a major component of the SSCC's budget. We're pleased to provide all the disk space our members need without charging individuals or projects, but please help keep costs down by using disk space wisely:

• Compress large files.
  
• Remove duplicate or unneeded files.
• Do not make copies of standard data files archived by CDE or other agencies or individuals.
  
• Archive files which you want to save but are no longer being used.
• Do not store any files which are not related to research.
• When you no longer need your project space, please alert the Consultant and we will archive the project on CD or DVD for you before removing the files.

Also see Managing Disk Space in Windows, Using Compressed Data in Windows, Managing Disk Space in Linux, and Using Compressed Data in Linux.

Owners of project directories are sent a report every six months listing duplicate files, files which are good candidates for compression, files which haven't been changed for a long time, and other information which can help with managing project space. We'll also be happy to generate a current report for you at any time.

Web Directories

In your Linux home directory you will find a directory called PUBLIC_web (Z:\PUBLIC_web from Windows). This directory can be used for a personal web site (though it must be focused on University business). The Linux directory /usr/global/web, available from Windows as \\sscunix\web, contains departmental and agency web sites. /usr/global/cgi is used for web scripts. See Publishing a Web Site on the SSCC's Web Server for more information.

All of these directories are automatically read by the web server, and files and folders placed in them will be available on the web.