[db_migrator]Do DB migration for buffer pool size change on Mellanox platform

[keboliu]

- What I did
Do DB migration for buffer pool size change introduced by new SDK, this is specifically for the Mellanox platform.

- How I did it
Advance the DB version to a new version 1_0_3, and add Mellanox specific DB migration functions.
Inside the function to migrate the buffer pool size to the latest values.

- How to verify it
test sonic to sonic upgrade from between various version and different topology.

- Previous command output (if the output of a command-line utility has changed)

- New command output (if the output of a command-line utility has changed)

[yxieca]

Can this change survive following scenarios:

1. Newly installed sonic image boots up, no minigraph, no config_db.json.
2. 0 size config_db.json (might be json parsing error in this case)
3. empty config_db.json file (contents is '{}')

db_migration towards config_db.json could be too late? migration is invoked after database has loaded the config_db.json into memory.

[keboliu]

Can this change survive following scenarios:

1. Newly installed sonic image boots up, no minigraph, no config_db.json.
2. 0 size config_db.json (might be json parsing error in this case)
3. empty config_db.json file (contents is '{}')

db_migration towards config_db.json could be too late? migration is invoked after database has loaded the config_db.json into memory.

enhanced the logic to handle more corner cases. the cases you mentioned have been covered.
per my test and code reading, it's true that db_migrator only update the Redis DB, and will keep config_db.json untouched, shall we add a step to dump configuration to config_db.json as the last step of db migration?

[liat-grozovik]

retest this please

[keboliu]

retest this please

[yxieca]

per my test and code reading, it's true that db_migrator only update the Redis DB, and will keep config_db.json untouched, shall we add a step to dump configuration to config_db.json as the last step of db migration?

I don't think we need to save in-memory db back to config_db.json. Because we can always migrate and migrate is one step of load config_db.json. If the migration failed, we definitely don't want to write back. right?

As such, I think you should leave /etc/sonic/config_db.sjon alone. So that it is consistent by itself. And an updated migration code could handle it in the future.

[prsunny]

per my test and code reading, it's true that db_migrator only update the Redis DB, and will keep config_db.json untouched, shall we add a step to dump configuration to config_db.json as the last step of db migration?

I don't think we need to save in-memory db back to config_db.json. Because we can always migrate and migrate is one step of load config_db.json. If the migration failed, we definitely don't want to write back. right?

As such, I think you should leave /etc/sonic/config_db.sjon alone. So that it is consistent by itself. And an updated migration code could handle it in the future.

Agree to Ying.

[keboliu]

per my test and code reading, it's true that db_migrator only update the Redis DB, and will keep config_db.json untouched, shall we add a step to dump configuration to config_db.json as the last step of db migration?

I don't think we need to save in-memory db back to config_db.json. Because we can always migrate and migrate is one step of load config_db.json. If the migration failed, we definitely don't want to write back. right?

As such, I think you should leave /etc/sonic/config_db.sjon alone. So that it is consistent by itself. And an updated migration code could handle it in the future.

@yxieca @prsunny then we are ok, I will not do further change to save migrated DB to config_db.json. Thanks.