Request for Comments: load balancing my CNFS buff files....

[John Kozubik]

I have 15 disks for my spool area, and I am using cnfs.

da1 - da7 are on one SCSI host adaptor, and da8-da15 are on a different SCSI 
host adaptor.

I created only two meta cycbuffs - one called 'BINARIES' and one called 
'ALLDREST' - I am seeking any and all comments on something I did in 
creating these two meta cycbuffs.

Basically, it occurred to me that my BINARIES meta cycbuff might have a very 
different disk/host adapter utilization pattern than my ALLDREST meta 
cycbuff.  So what I did, is instead of giving all the disks on SCSI host 
adaptor #1 (7 disks in all) to BINARIES and all the disks on SCSI host 
adaptor #2 (8 disks in all) to ALLDREST, is I alternated one disk from one 
host adaptor and one disk from the other host adaptor, until all were used 
up.

So in essence, the BINARIES meta cycbuff is a stripe across both host 
adaptors and so is the ALLDREST meta cycbuff.  Here is what it looks like in 
cycbuff.conf:

metacycbuff:ALLDREST:1,8,2,9,3,10,4,11
metacycbuff:BINARIES:5,12,6,13,7,14,15

Note that the numbers are NOT consecutive - the buffer named '1' is the 
first disk on the first host adaptor, but the buffer named '8' is the first 
disk on the second host adaptor.

What I hoped to gain:

Basically, I have no idea what the utilization pattern of the BINARIES meta 
cycbuff vs. the ALLDREST meta cycbuff is - what I _do_ know is that they are 
_different_ and therefore one of them must utilize a SCSI host adaptor 
differently than the other, and therefore, although I am degrading 
performance for the meta cycbuff that utilizes its controller the least, 
over the aggregate of _BOTH_ meta cycbuff files, I am decreasing SCSI host 
adaptor congestion, and thus receiving higher overall disk performance.

Any comments?

I realize that the gain is most likely very small, and also not likely to be 
noticed, but it is nice to be correct (if I am, indeed, correct)

-john
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