I was tempted to reply with Dave Boyes' answer.   :-)

The major factor w/r/t wasted space on 3390 geometry is the block size,
for which 4K is most efficient and also what Linux and CMS default to.  So
don't worry so much what model to use  (in terms of space).  But bandwidth
... ahh,  now there is something to consider.

YOU MAY want to do some I/O load balancing,  where smaller devices as
presented by the storage system will be of help.  But this gets really
complicated because you also need to pay attention to the I/O channels.
(That is,  if you have 15 mod 3s on one path -vs- five mod 9s,  is there
really a difference?)

-- R;





"Lionel B. Dyck" <[EMAIL PROTECTED]>

Sent by: Linux on 390 Port <[email protected]>




05/09/2007 12:41 PM
Please respond to Linux on 390 Port <[email protected]>

From
"Lionel B. Dyck" <[EMAIL PROTECTED]>
To
[email protected]
cc

Subject
dasd (3390) model usable space






We are trying to decide which 3390 model to configure in our incoming
storage device (probably emc but could be shark). The point of interest is

which model provides the least amount of 'wasted' space due to overhead
requirements.  Here is a chart that I've cobled together from a few web
sites and you'll notice that the usable bytes column is empty.


Disk Type
Data cylinders
Tracks per cylinder
Bytes per track
Bytes per cylinder
Bytes per module
GB per module
Spare Cylinders
Usable Bytes
3390-1
1113
15
56,664
849,960
946,005,480
0.95
1

3390-2
2226
15
56,664
849,960
1,892,010,960
1.89
1

3390-3
3339
15
56,664
849,960
2,838,016,440
2.84
1

3390-9
10017
15
56,664
849,960
8,514,049,320
8.51
3

3390-27
32760
15
56,664
849,960
27,844,689,600
27.84
3

3390-54
65520
15
56,664
982,800
55,689,379,200
55.69
3


Thanks

Lionel B. Dyck, Consultant/Specialist
Enterprise Platform Services, Mainframe Engineering
KP-IT Enterprise Engineering, Client and Platform Engineering Services
(CAPES)
925-926-5332 (8-473-5332) | E-Mail: [EMAIL PROTECTED]
AIM: lbdyck | Yahoo IM: lbdyck
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