SCP Disks

Last updated: 2005-Sep-16

SCP disks are divided into a number of different categories:

1. Home Disk
2. User Disks
3. System Disks
4. Global Scratch Disks
5. Local Scratch Disks
6. Temporary Scratch Disks
7. Deepsearch Data Disks

/home/astro10 is the disk where all the home directories are stored. (The PC home directories are on /home/lilys, but this is on the same disk partition as /home/astro10.) This disk is backed up once a week, and as such is our most precious space. It is a 40GB partition, shared amongst all the SCP computer users.

This is where you store all your usual home directory sorts of things. It's also where you should put source code, papers, slides and overheads, proposals, IDL programs, etc. You should not put image data files on this disk! Because it's only 40GB, and shared between everybody, we simply cannot afford to have people filling this space up with data. The astronomical data we deal with nowadays is too space consuming to be put in a place that's backed up weekly. Especially given that usually once the data is reduced, it doesn't change, it simply doesn't make sense to use up regularly backed up space on it.

/home/astro10 (and /home/lilys) is served by panisse, and is available on all SCP computers.

Right now, there is only one user disk, /home/astro1. This is a 21GB disk that is not backed up. You should store the same sorts of things here that you store in your home directory, keeping in mind that the home directory is what is backed up most often. Your directory on /home/astro1 should be

/home/astro1/yourname

These disks are not available for general use, but are listed here for completeness. They serve either some system administration function, or are a repository for Deepsearch information. Technically, the root and /usr disks on each individual computer should be listed here as well.

Note that even though these aren't available for general user use, many Deepsearch users will modify files on some of these disks, particularly /home/astro9 (when Deep/IDL code is updated) and /home/panisse (the web disk).

These disks are non-backed up disks which you should consider as "general workspace". This is where you should put data you're working on reducing (unless you've got some personalized local scratch space). This data will not be backed up unless you do it yourself.

These scratch disks are mounted on our file servers. They are accessible from any of the SCP workstations.

Sometimes, some of the disks on rustica will need to be commandeered as work space for search runs. If a search run is impending, you may be asked to completely clear off all of your space used on a scratch disk. Right now, this is most likely to happen on /home/astro45, but it may be on different disks in the future. You're more likely to avoid problems with this if you use scratch space on zacharys and panisse. You will probably see better performance there, anyway, because most of the workstations are on the same subnet as zacharys and panisse. (Rustica is on a different subnet.) For use with the McDonlads cluster, scratch space on Rustica is your best bet.

Many of the workstations have one or more disks mounted locally. It is to your advantage to use the scratch space local to your computer. Because disk accesses to these disks do not go over the network, performance should be better, and you avoid bogging down the network for everybody else.

It is entirely possible to access these disks from other workstations. However, I recommend that you avoid this except when it's necessary, for various technical reasons of stability that I don't want to go into at the moment. If you need scratch space accessible from lots of different computers, consider using global scratch instead. If you need to use disk space primarily from your own workstation, then a local scratch disk is a good thing.

Some of these scratch disks are designated to be used only by one person. Generally, this will tend to be the person on whose workstation the disk is mounted, for obvious reasons.

Temporary Scratch Disks

Lots of computers have a local disk /scratch which is not exported anywhere. You should, in general, not try to use this space. These directories are subject to immediate deletion without warning at any time. They are there in hopes that one day we'll get a queue manager that can rationally manage our workstations in addition to the McDonalds cluster; these directories will then form local workspace. In the mean time, they may be used manually during search runs for local workspace.

Deepsearch Data Disks

There are several disks which are devoted to deepsearch data, some more to nearby99 data, and maybe even a few to snfactory data. Most of the deepsearch data disks are RAID partitions nowadays, so that the data won't be lost if one disk dies. (It will still be lost if somebody stupidly deletes it, however.) You should NOT make subdirectories in these directories, nor should you work in these directories. These directories are ONLY for data which is in the deepsearch (or nearby99) database.