Huawei OceanStor V3 Series - Page 18

Figure 1-2 Writing process in synchronous remote replication mode
Primary
LUN
Host
LOG
Secondary
LUN
2
6
4
3
6
Secondary
Cache
Primary
Cache
DCL
4
5
1
3
Remote replication links
Primary
storage system
Secondary
storage system
Data block N
Determination
1
2
4
3
6
Primary
cache
Primary
LUN
Secondary
LUN
Secondary
cache
3
4
RM
Data block N
Data block N
Records the difference in the LOG
Write I/O result
5
Write I/O result
· Saves the log to the DCL upon any write failure
· Deletes the log if all writes are successful
RM
LOG
Write I/O result
RM: Remote replication management module.
LOG: Records data write logs.
DCL: Data change log.
NOTE
The DCL is stored on all the disks in the disk domain and four-disk RAID 1 is used for data protection while
storage system logs are stored on coffer disks.
1. The host sends a write I/O request to the RM.
2. The RM records the write I/O request in the LOG.
OceanStor V3 Series
Remote Replication Feature Guide for Block
1 Feature Description
Issue 06 (2018-01-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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