[fast-reboot] Backup database after syncd/swss stopped

[stepanblyschak]

What I did

Backup DB after syncd and swss are stopped. I observed an issue with fast-reboot that in a rare circumstances a queued FDB event might be written to ASIC_DB by a thread inside syncd after a call to FLUSHDB ASIC_DB was made.
That left ASIC_DB only with one record about that FDB entry and caused syncd to crash at start:

Mar 15 13:28:42.765108 sonic NOTICE syncd#SAI: :- Syncd: syncd started
Mar 15 13:28:42.765268 sonic NOTICE syncd#SAI: :- onSyncdStart: performing hard reinit since COLD start was performed
Mar 15 13:28:42.765451 sonic NOTICE syncd#SAI: :- readAsicState: loaded 1 switches
Mar 15 13:28:42.765465 sonic NOTICE syncd#SAI: :- readAsicState: switch VID: oid:0x21000000000000
Mar 15 13:28:42.765465 sonic NOTICE syncd#SAI: :- readAsicState: read asic state took 0.000205 sec
Mar 15 13:28:42.766364 sonic NOTICE syncd#SAI: :- onSyncdStart: on syncd start took 0.001097 sec
Mar 15 13:28:42.766376 sonic ERR syncd#SAI: :- run: Runtime error during syncd init: map::at
Mar 15 13:28:42.766376 sonic NOTICE syncd#SAI: :- sendShutdownRequest: sending switch_shutdown_request notification to OA for switch: oid:0x0
Mar 15 13:28:42.766518 sonic NOTICE syncd#SAI: :- sendShutdownRequestAfterException: notification send successfully

How I did it

Backup DB after syncd/swss have stopped.

How to verify it

Run fast-reboot.

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)