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[202405] Restart PMON when SWSS flushes APPL_DB on Arista SKUs that use media_settings.json#1080

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arlakshm merged 1 commit intoAzure:202405from
arista-nwolfe:202405-restart-pmon-on-swss-flush
May 2, 2025
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[202405] Restart PMON when SWSS flushes APPL_DB on Arista SKUs that use media_settings.json#1080
arlakshm merged 1 commit intoAzure:202405from
arista-nwolfe:202405-restart-pmon-on-swss-flush

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@arista-nwolfe arista-nwolfe commented May 2, 2025

Workaround for sonic-net/sonic-buildimage#21902

SWSS startup causes APPL_DB to be flushed.
This results in PORT_TABLE:Ethernet# losing it's media_settings tunings populated by XCVRD.

Without this change (tuning lost):

sonic-db-cli -n asic0 APPL_DB hgetall "PORT_TABLE:Ethernet96"
{'alias': 'Ethernet13/1', 'asic_port_name': 'Eth96', 'core_id': '0', 'core_port_id': '13', 'index': '13', 'lanes': '40,41,42,43', 'num_voq': '8', 'role': 'Ext', 'speed': '100000', 'admin_status': 'up', 'description': 'ARISTA13T3:Ethernet1', 'fec': 'none', 'mtu': '9100', 'pfc_asym': 'off', 'tpid': '0x8100', 'oper_stat
us': 'up', 'flap_count': '1', 'main': '0x4e,0x4e,0x53,0x4b', 'post1': '0xffffffea,0xffffffea,0xffffffea,0xffffffec', 'post2': '0x0,0x0,0x0,0x0', 'post3': '0x0,0x0,0x0,0x0', 'pre1': '0xfffffffb,0xfffffffb,0xfffffffb,0xfffffffb', 'pre2': '0x0,0x0,0x0,0x0', 'last_up_time': 'Thu Apr 03 16:32:03 2025'}

systemctl restart swss@0.service

sonic-db-cli -n asic0 APPL_DB hgetall "PORT_TABLE:Ethernet96"
{'alias': 'Ethernet13/1', 'asic_port_name': 'Eth96', 'core_id': '0', 'core_port_id': '13', 'index': '13', 'lanes': '40,41,42,43', 'num_voq': '8', 'role': 'Ext', 'speed': '100000', 'admin_status': 'up', 'description': 'ARISTA13T3:Ethernet1', 'fec': 'none', 'mtu': '9100', 'pfc_asym': 'off', 'tpid': '0x8100', 'oper_stat
us': 'up', 'flap_count': '1', 'last_up_time': 'Thu Apr 03 17:41:08 2025'}

With this change (tuning preserved):

sonic-db-cli -n asic0 APPL_DB hgetall "PORT_TABLE:Ethernet96"
{'alias': 'Ethernet13/1', 'asic_port_name': 'Eth96', 'core_id': '0', 'core_port_id': '13', 'index': '13', 'lanes': '40,41,42,43', 'num_voq': '8', 'role': 'Ext', 'speed': '100000', 'admin_status': 'up', 'description': 'ARISTA13T3:Ethernet1', 'fec': 'none', 'mtu': '9100', 'pfc_asym': 'off', 'tpid': '0x8100', 'oper_stat
us': 'up', 'flap_count': '1', 'main': '0x4e,0x4e,0x53,0x4b', 'post1': '0xffffffea,0xffffffea,0xffffffea,0xffffffec', 'post2': '0x0,0x0,0x0,0x0', 'post3': '0x0,0x0,0x0,0x0', 'pre1': '0xfffffffb,0xfffffffb,0xfffffffb,0xfffffffb', 'pre2': '0x0,0x0,0x0,0x0', 'last_up_time': 'Thu Apr 03 16:32:03 2025'}

systemctl restart swss@0.service

sonic-db-cli -n asic0 APPL_DB hgetall "PORT_TABLE:Ethernet96"
{'alias': 'Ethernet13/1', 'asic_port_name': 'Eth96', 'core_id': '0', 'core_port_id': '13', 'index': '13', 'lanes': '40,41,42,43', 'num_voq': '8', 'role': 'Ext', 'speed': '100000', 'admin_status': 'up', 'description': 'ARISTA13T3:Ethernet1', 'fec': 'none', 'mtu': '9100', 'pfc_asym': 'off', 'tpid': '0x8100', 'oper_stat
us': 'up', 'flap_count': '1', 'main': '0x4e,0x4e,0x53,0x4b', 'post1': '0xffffffea,0xffffffea,0xffffffea,0xffffffec', 'post2': '0x0,0x0,0x0,0x0', 'post3': '0x0,0x0,0x0,0x0', 'pre1': '0xfffffffb,0xfffffffb,0xfffffffb,0xfffffffb', 'pre2': '0x0,0x0,0x0,0x0', 'last_up_time': 'Fri Apr 04 17:12:59 2025'}

I also see the message in syslog that pmon is restarted right after the dbs are flushed:

NOTICE root: Chassis db clean up for swss0. Number of SYSTEM_LAG_TABLE entries deleted: 8
NOTICE root: Restarting pmon service...

This is a cast specifically for MSFT-202405 for Arista T2 SKUs, we'll submit a change that applies more generally to all media_settings.json SKUs in master.

@arista-nwolfe arista-nwolfe requested a review from lguohan as a code owner May 2, 2025 22:06
@arista-nwolfe arista-nwolfe mentioned this pull request May 2, 2025
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@arlakshm arlakshm merged commit a9a78ca into Azure:202405 May 2, 2025
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bingwang-ms pushed a commit that referenced this pull request Jan 16, 2026
@mssonicbld
[submodule] Update submodule sonic-swss-common to the latest HEAD aut…
5a28c57 
…omatically (#24121)

#### Why I did it
src/sonic-swss-common
```
* 36a8519 - (HEAD -> master, origin/master, origin/HEAD) Add c-api/Rust wrappers for SonicV2Connector (#1080) (21 hours ago) [Qi Luo]
* f9cc568 - Fix trixie compilation and add Trixie to PR pipeline (#1069) (29 hours ago) [Saikrishna Arcot]
```
#### How I did it
#### How to verify it
#### Description for the changelog
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@lguohan lguohan Awaiting requested review from lguohan lguohan is a code owner

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@arista-nwolfe @arlakshm