IBM DS8880 Series Introduction And Planning Manual page 104

Standard drive enclosures
For storage systems that support both standard drive enclosures and High
Performance Flash Enclosures Gen2, follow these configuration rules when you
order storage features for standard drive enclosures. All-flash systems do not
support standard drive enclosures.
Standard drive enclosures
Drive sets
Storage enclosure fillers
Device adapters
Drive cables
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DS8880 Introduction and Planning Guide
Storage enclosures are installed from the bottom to the top of each base or
expansion frame. Depending on the number of drive sets that you order
for the expansion frame, you might be required to fully populate the
standard drive enclosure before you can order the next required drive sets.
Each standard high-density drive enclosure requires a minimum of eight
flash drives or disk drives. The drive features that you order for the
standard drive enclosure must be of the same type, capacity, and speed.
Each base frame requires a minimum of one drive set.
One filler feature provides a set of 8 or 16 fillers. Two filler features are
required if only one drive-set feature is ordered for a standard
drive-enclosure pair. One filler feature is required if two drive-set features
are ordered for the standard drive-enclosure pair.
Device adapters are ordered in pairs. A minimum of one pair is required
for each base frame.
For DS8884, configurations with 64 GB of memory can have two
device-adapter pairs, and configurations with 128 GB or 256 GB of memory
can have four device-adapter pairs.
For DS8886, configurations with 8-core processors can have four
device-adapter pairs, and configurations with 16-core and 24-core
processors can have eight device-adapter pairs.
At least one drive cable set is required to connect the disk drives to the
device adapters.
The disk-drive cable groups must be ordered as follows:
v If the disk drives connect to device adapters within the same base frame,
order disk drive cable group A.
v If the disk drives connect to device adapters within the first expansion
frame, order disk drive cable group B.
v If the disk drives are in a second expansion frame, order disk drive cable
group C.
v If the disk drives are in a third expansion frame (85E, 86E), order disk
drive cable group D.
v If the disk drives are in a fourth expansion frame (85E, 86E), order disk
drive cable group E.
v If the disk drives are in a remote expansion frame (up to 20 meters from
the base frame), order extended disk drive cable group C, D, or E.