Where are the scratch areas?
The following table describes all scratch areas
name |
location |
Size |
Usage |
/scratch/fs1a |
Roque |
10 GB |
for general use |
/scratch/fs4a |
SLO |
11 GB |
for CFG use* |
/scratch/fs4b |
SLO |
67 GB |
for Astronomy use* |
/scratch/inta |
INT |
100 GB |
for INT Observer's use |
/scratch/intb |
INT |
75 GB |
for INT Observer's use |
/scratch/jkta |
JKT |
8 GB |
for JKT Observer's use |
/scratch/whta |
WHT |
99 GB |
for WHT Observer's use |
/scratch/whtb |
WHT |
60 GB |
for WHT Observer's use |
/scratch/whtc |
WHT |
16 GB |
for WHT Observer's use |
-
Any recent additions to this list?
-
If you want to see if any more have appeared since this documentation was
last updated type the following command
Use cut-and-paste from this example!
niscat auto_scratch.org_dir | sort
|
-
Any recent changes to size?
-
To see the size you must use two commands. First wake up the automounter
using ls then use df
Use cut-and-paste from this example!
ls /scratch/fs1a > /dev/null ; df -k /scratch/fs1a
|
-
Notes
-
the /scratch/whtc is much bigger because it is served from a RAID array.
The other RAID operated by the CFG is used as a data area in the INT.
Any restrictions on use of scratch area?
If you are not the observer please do not use the areas reserved for "...
Observer's Use"
At the time of writing the trivially small /scratch/whtb is served from
a poor old sunos sparc. This sparc if feeble but has a role in the Real-Time
Display. To conserve resources on this old sparc the area /scratch/whtb
can not be accessed outside of the WHT.
Which scratch area should I use?
-
Usually you will use a scratch area which is nearest to you. If working
at the Sea-Level Office you would use /scratch/fs4a. If working at the
Roque you would use /scratch/fs1a. If you are the observer then use the
scratch area associated with the telescope where you have your observing
run.
-
The show_scratch command which was is in /usr/local/bin is not available
- sorry
please keep the area tidy - create a top level directory derived from your
name if on a general scratch area but by DATE if you are the observer.
Example
cd /scratch/fs1a
mkdir guest12
cd guest12
...
Example
cd /scratch/inta
mkdir 20000831
cd 20000831
...
What if the scratch area is full?
Scratch disk space management is dynamic. There is no need for the system
manager or anyone else to be asked to delete files. Every 4 hours a crontab
job examines free capacity on the scratch disks. If the free capacity on
any disk drops below 20% free then the oldest files on the disk are deleted
if they are less than 21 days old. By oldest files we mean the files with
the oldest accession date. Files are unconditionally deleted after 60 days
of not being accessed.
IMPORTANT
-
If you restore files from a tape to disk then they will appear to be "old".
To avoid them being selected as targets you should use a dummy tar job
to access all the restored files. Use the null device (/dev/null) for output
- or simply a dummy tape. Using a scratch area with lots of free space
will help to avoid this problem.
-
If you want scratch disk space then just go ahead and use it. If the disk
fills up to 80% and you want more then fill it beyond 80% and either use
another disk or wait for the disk monitor to react in at most 4 hours.
The reaction time of the disk monitor is generally going to be faster than
calling the system manager. Average response is 2 hour. In the meantime
you could use another disk.
-
* This system does not operate on these disks.
How secure are my files?
Under the rules of the dynamic disk management you are guaranteed 21 days.
The scratch areas are not backed up to tape. In the event of a disk failure
or the accidental erasure of your files by another user you could lose
your files. You could also lose your files if they are more than 21 days
old and you or another user reduces free disk capacity below 20%. If you
want to secure your files it is your responsibility to make a backup tape.
Please obtain a dat tape and use "tar" or "dump" of your directory.
If by security you mean "privacy" the answer is dependent on the protection
you give to your files and in particular the protection code on the directory
you create in /scratch/lpssX. Use chmod to restrict access from other users.
This page is available on-line as
http://www.ing.iac.es/~cfg/pub_notes/scrdskman.htm