IBM DS8880 Series, Introduction And Planning Manual

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On open volumes with 520 byte blocks, you can select one of the supported LUN
sizes that are used on IBM i processors to create a LUN. The operating system uses
8 of the bytes in each block. This leaves 512 bytes per block for your data. Variable
volume sizes are also supported.
Table 23 shows the disk capacity for the protected and unprotected models.
Logically unprotecting a storage LUN allows the IBM i host to start system level
mirror protection on the LUN. The IBM i system level mirror protection allows
normal system operations to continue running in the event of a failure in an HBA,
fabric, connection, or LUN on one of the LUNs in the mirror pair.
Note: On IBM i, logical volume sizes in the range 17.5 GB to 141.1 GB are
supported as load source units. Logical volumes smaller than 17.5 GB or larger
than 141.1 GB cannot be used as load source units.
Table 23. Capacity and models of disk volumes for IBM i hosts running IBM i operating
system
Size Protected model Unprotected model
8.5 GB A01 A81
17.5 GB A02 A82
35.1 GB A05 A85
70.5 GB A04 A84
141.1 GB A06 A86
282.2 GB A07 A87
1 GB to 2000 GB 099 050
On CKD volumes, you can specify an exact cylinder count or a standard volume
size to create a LUN. The standard volume size is expressed as an exact number of
Mod 1 equivalents (which is 1113 cylinders). The unit of storage allocation for CKD
volumes is one CKD extent. The extent size for a CKD volume is either exactly a
Mod-1 equivalent (which is 1113 cylinders), or it is 21 cylinders when using the
small-extents option. Any logical volume that is not an exact multiple of 1113
cylinders (1 extent) does not use all the capacity in the last extent that is allocated
to the logical volume. For CKD volumes that are created with 3380 track formats,
the number of cylinders (or extents) is limited to either 2226 (1 extent) or 3339 (2
extents). For CKD volumes that are created with 3390 track formats, you can
specify the number of cylinders in the range of 1 - 65520 (x'0001' - x'FFF0') in
increments of one cylinder, for a standard (non-EAV) 3390. The allocation of an
EAV volume is expressed in increments of 3390 mod1 capacities (1113 cylinders)
and can be expressed as integral multiples of 1113 between 65,667 - 1,182,006
cylinders or as the number of 3390 mod1 increments in the range of 59 - 1062.
Extended address volumes for CKD
Count key data (CKD) volumes now support the additional capacity of 1 TB. The 1
TB capacity is an increase in volume size from the previous 223 GB.
This increased volume capacity is referred to as extended address volumes (EAV)
and is supported by the 3390 Model A. Use a maximum size volume of up to
1,182,006 cylinders for the IBM z/OS. This support is available to you for the z/OS
version 12.1, and later.
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DS8880 Introduction and Planning Guide