I/O modes

Ops Center High Availability User Guide
Version
10.8.x
File Size
3.9 MB
Audience
anonymous
Part Number
MK-99ADM003-10

You should understand the I/O actions on the P-VOL and the S-VOL of a GAD pair.

The following table lists and describes the GAD I/O modes. As shown in the following table, the I/O mode terms displayed by the user interfaces are slightly different.

I/O mode

Read processing

Write processing

I/O mode

CCI 1

HDvM - SN

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.

Block2

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.