Hello,
I recommend using the SmartMigration feature which is a key services migration technology, which migrates services from the source LUN to the destination LUN without interrupting the host services and allows the destination LUN to take over the services of the source LUN.
Please find the manual of how to use it:
https://support.huawei.com/enterprise/en/doc/EDOC1000181479/426cffd9/about-this-document