John Eells wrote:
[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.")
Eyyuuup.
Thanks.
I still get a kick out the fact it would take
more that 335,000,000 of these guys to back up
one 64-bit AS, but the maximum number of page
volumes supported is 253.
Kind regards,
-Steve Comstock
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