BGSAVEStart a snapshot save in the background.
| 構文 | BGSAVE |
| グループ | server |
| 引数の数 | 1 |
| 導入バージョン | 1.0.0 |
| フラグ | write, admin |
| 計算量 | O(S) fan-out; O(N/S) copy-on-write freeze per shard on the reactor, then serialise off-thread |
| Redis 互換性 | differs: replies +OK rather than Redis's status line, and writes one dump per shard |