Hitachi G1000 - Relationship between GAD Status, Pair Status, and I;O Mode

I/O mode
Read processing Write processing
I/O
mode
CCI
1
HCS
Mirror
(RL)
L/M Mirror
(Read
Local)
Sends data from the
storage system that
received a read request to
the server.
Writes data to the P-VOL
and then the S-VOL.
Local L/L Local Sends data from the
storage system that
received a read request to
the server.
Writes data to the volume
on the storage system
that received a write
request.
Block
2
B/B Block Rejected (Replies to illegal
requests).
Rejected (Replies to illegal
requests).
Notes:
1. In CCI, the I/O mode is displayed as <read processing>/<write processing> in
which L indicates Local, M indicates Mirror, and B indicates Block (for example, L/L
indicates Local read processing and Local write processing).
2. For volumes whose I/O mode is Block, a response indicating that the LU is undefined
is returned to the Report LUN and Inquiry commands. Therefore, servers cannot
identify a volume whose I/O mode is Block, or the path of this volume is blocked.
Related topics
• Monitoring GAD status on page 1-10
Relationship between GAD status, pair status, and I/O mode
The following table lists the GAD statuses and describes the relationship
between the GAD status, pair status, and I/O mode. "N" indicates that pair
status or I/O mode cannot be identified due to a failure in the storage
system.
GAD
status
When to
suspend
P-VOL S-VOL Volume
that has
the latest
data
Pair
status
I/O mode
Pair
status
I/O mode
Simplex Not
applicable
SMPL Not
applicable
SMPL Not
applicable
Not
applicable
Mirroring Not
applicable
INIT Mirror (RL) INIT Block P-VOL
Not
applicable
COPY Mirror (RL) COPY Block P-VOL
Mirrored Not
applicable
PAIR Mirror (RL) PAIR Mirror (RL) P-VOL and
S-VOL
Suspended Pair
operation
PSUS Local SSUS Block P-VOL
Overview of global-active device
1-13
Hitachi Virtual Storage Platform G1000 Global-Active Device User Guide