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DS4000 storage expansion enclosure ID settings
Some DS4000 storage expansion enclosures, such as the EXP710/EXP700/
EXP100/EXP500, have an enclosure ID switch that is used to identify the DS4000
storage expansion enclosure on a fibre channel loop. The enclosure ID switch is
located on the back of the unit. Other DS4000 storage expansion enclosures, such
as the EXP810, do not have an enclosure ID switch because the controller
automatically sets the enclosure ID number.
If required, use a small screwdriver or the tip of a pen to push the small buttons
above and below each enclosure ID digit to change the enclosure ID setting. Press
the button located above the digit to lower the digit by one. Press the button located
below the digit to raise the digit by one.
Note: Some DS4000 storage expansion enclosures ship with a panel installed over
the enclosure ID switch to prevent the enclosure ID from being changed
accidentally. If your DS4000 storage expansion enclosure has a protective
panel over the ID switch, use a pencil or a small screwdriver to change the
enclosure ID.
Each storage expansion enclosure in a DS4000 Storage Subsystem drive loop must
have a unique enclosure ID. DS4000 controllers use a combination of the enclosure
ID and the number of the physical slot that a hard drive occupies to create a unique
fibre channel loop address or arbitrated loop physical address (AL_PA) for each
drive in a fibre channel drive loop. The enclosure ID consists of two digits, a tens
digit (x10) and ones digit (x1).
Attention: When connecting storage expansion enclosures, you must use the
tens digit (x10) enclosure ID setting to distinguish different redundant drive loop
pairs and use the ones digit (x1) enclosure ID setting to distinguish storage
expansion enclosures IDs within a redundant drive loop pair. For example, in a
DS4500 configuration with sixteen EXP710 storage expansion enclosures
distributed equally across one redundant drive loop pair, the recommended
enclosure ID settings for the enclosures are shown in Table 16 on page 67. EXP810
storage expansion enclosures automatically set their enclosure IDs to be unique in
a drive loop pair.
Give each storage expansion enclosure in a redundant drive loop pair a unique
ones digit (x1) ID. This setting will enforce hard AL_PAs (unchangeable between
fibre channel Loop Initializations [LIPs]) for the drives and facilitate drive loop
problem troubleshooting in the event of an error. If the one's digits are not unique,
two or more devices will have the same hard AL_PA. In such a case, the DS4500
controller will use soft AL_PAs for the devices that have identical hard AL_PAs.
The problem with soft AL_PAs addressing is that addresses may change between
LIPs. This possibility increases the difficulty of troubleshooting drive loop problems,
since one cannot easily ascertain whether the same device with a different address
or different device may be causing a problem. In addition, drive loop errors might be
randomly posted in the DS4500 subsystem Major Event Log (MEL) when
intermixing EXP100s, EXP710 and EXP810s in the same redundant drive loop pair
with a soft AL_PA addressing scheme.
Connecting secondary interface cables
This section is applicable to (direct) out-of-band management configurations only. If
your configuration uses host-agent (in-band) management, skip this section.
Chapter 3. Cabling the storage subsystem 103