Steve Comstock wrote:
I've been trying to do a little research and
I'm getting mixed results. What I would like
to find is: what is the capacity of the largest
logical 3390 model supported by z/OS?
Figures I've seen range from 8.5 GiB to 55 GiB,
from different sources.
You folks are where the rubber meets the road,
can anyone tell me the current largest supported
logical 3390 model and its capacity? [and point
me to the best source for this for the future]
<snip>
Up to 64K cylinders are supported on DS6000 and DS8000 devices.
From "Preview: IBM z/OS V1.7 and z/OS.e V1.7: World-class
computing for On Demand Business," IBM United States Software
Announcement 205-034, dated
February 15, 2005:
"TotalStorage® DS6000 and DS8000: z/OS V1.4 and above will
support the TotalStorage DS6000 and DS8000, which offer a
simplified storage management system. For zSeries and z/OS
environments, these storage devices support a new 65,520 cylinder
3390 volume. This new volume option has a capacity of
approximately 55.7 GB."
And:
"These functions are available now on z/OS V1.4 and above. For
information about the requirements for using these functions,
refer to the DS6000 and DS8000 Preventive Service Planning (PSP)
buckets. The PSP UPGRADE names are 1750DEVICE and 2107DEVICE."
Now, getting any more precise an answer than that (if you wanted
one) is more difficult. The track length of a 3390 volume is
56,664 bytes. My trusty calculator tells me that 56,664 * 15 *
65,520 is 55,689,379,200 bytes, or a bit under 52GiB. However,
this calculation ignores things like VTOC/VTOCIX space, block
size, cell size, count fields, and key lengths, so actual data
capacity will be somewhat less.
There are formulas, somewhere, but I don't have a reference handy
for these exact devices, and the formulas apply at the data
set level. With the formulas in hand, one could determine the
exact maximum capacity of a volume...but the number wouldn't
really be very useful. When they're full, they're full. (As the
farmer says of his pickup truck, "When the bumper hits the
ground, that's all she'll carry.")
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
[EMAIL PROTECTED]
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