[daip] optimizing AIPS

[Eric Greisen]

Kristy Dyer writes:

 > One question I wanted to ask you -- How would you optimize AIPS for low 
 > frequency data reduction?
 > 
 > I have two IDE and two SCI drives:
 > 
 > /dev/sda1              34G   28G  5.4G  84% /local/data/lark
 > /dev/sdb1              34G   33G  290M 100% /local/data/lark2
 > /dev/hdb1             184G   15G  169G   8% /local/data/lark3
 > /dev/hdd1             184G   66G  119G  36% /local/data/lark4

     I think I hate you - I had to beg to get an old 9 Gbyte drive
added to my machine and that will not hold my data enough to work on
them.

I think that IDE drives are not as slow as one might think.  In many
tests we did not see any degredation of performance with them.  One
test with spectral-line data did show a real difference but I did not
do that test and am suspicious.  You could try Y2K huge or large with
everything forced to lark2 say and repeat it with everything forced to
lark3 (i.e. set BADDISK, TDISK, MDISK, DDISK).

 > 
 > So what I've done at the moment is install AIPS on /local/data/lark, and 
 > put the main two disk areas on /local/data/lark and /local/data/lark2 so 
 > that I'm reading and writing to scuzzy drives. Is it bad to have the AIPS 
 > binaries on the same drive that I'm reading or writing to? Then projects 
 > I'm not actively working on are the (larger) IDE drives.

Eric