Sun Storage 3510 FC Array
 

GCS>Sun Microsystems>Storage - Disk>Modular Disk - 3xxx Arrays
 

The SES device in the top slot of the chassis is connected to Loop A, which is the first drive channel. The bottom SES device is connected to Loop B, which is the second drive channel. This may lead to an incorrect assumption that loop A
is always associated  with channel 2 or the top controller slot of the array.
While drive channels are fixed physical associations (channel 2 / top slot and channel 3 / bottom slot) , loop references are relative .
sccli>  show loop-map channel 2
15 devices found in loop map
=== Channel Loop Map retrieved from CH 2 ID 12 ===
AL_PA   SEL_ID  SEL_ID  TYPE    ENCL_ID SLOT
(hex)   (hex)   (dec)
-----   -----   -----   ----    ------  ----
CE      0F      15      RAID    N/A     N/A  <<<<   lower controller acting as primary . Arbitrary assignment to  loop A
D4      0B      11      DISK    0       11
DC      06      6       DISK    0       6
D5      0A      10      DISK    0       10
DA      07      7       DISK    0       7
D3      0C      12      SES     0       N/A
D1      0E      14      RAID    N/A     N/A
E8      01      1       DISK    0       1
E1      04      4       DISK    0       4
E4      02      2       DISK    0       2
E2      03      3       DISK    0       3
E0      05      5       DISK    0       5
EF      00      0       DISK    0       0
D9      08      8       DISK    0       8
D6      09      9       DISK    0       9

In this example, the show disks command indicates disk 34 is BAD:
sccli> show disks
Ch     Id      Size   Speed  LD     Status     IDs Rev
----------------------------------------------------------------------------
2     34       N/A   N/A    NONE   BAD        SEAGATE ST373307FSUN72G   0207
S/N 3HZ13X4400007340
The show redundancy command displays the Primary Controller in the bottom slot:
sccli> show redundancy
Primary controller serial number: 8003752
Primary controller location: Lower
Redundancy mode: Active-Active
Redundancy status: Enabled
Secondary controller serial number: 8000596
Looking at the output from the show bypass command for this bad drive, channel 2 SES, disk 34 is bypassed on loop B and unbypassed on loop a.  But according to channel 3 SES, it appears as the opposite of channel 2.
sccli> show bypass device channel 2 loop a
CH      ID      TYPE    ENCL    LOOP    BYP-STATUS      ATTRIBUTES
--      --      ----    ----    ----    ----------      SHF-------
2       34      DISK    JBOD    LOOP-A  Unbypassed      --F
sccli> show bypass device channel 2 loop b
CH      ID      TYPE    ENCL    LOOP    BYP-STATUS      ATTRIBUTES
--      --      ----    ----    ----    ----------      SHF-------
2       34      DISK    JBOD    LOOP-B  Bypassed        -HF
sccli> show bypass device channel 3 loop a
CH      ID      TYPE    ENCL    LOOP    BYP-STATUS      ATTRIBUTES
--      --      ----    ----    ----    ----------      SHF-------
3       34      DISK    JBOD    LOOP-A  Bypassed        -HF
sccli> show bypass device channel 3 loop b
CH      ID      TYPE    ENCL    LOOP    BYP-STATUS      ATTRIBUTES
--      --      ----    ----    ----    ----------      SHF-------
3       34      DISK    JBOD    LOOP-B  Unbypassed      --F
Looking at the bypass state, be aware Loop A may not always be associated with the top slot (channel 2) and may be represented from the bottom slot and vice versa for loop B. This is because what is shown is the view from the SES processor which always considers its view as loop A, irrespective of the slot.

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