Make it store its internal `zap.Logger`'s level. Also, make all the
components to accept internal `logger.Logger` instead of `zap.Logger`; it
will simplify future refactor.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Degraded mode allows us to operate without an SSD,
thus writecache should be unavailable in this mode.
Signed-off-by: Evgenii Stratonikov <evgeniy@morphbits.ru>
Allow user to initiate flushing objects from a writecache.
We need this in 2 cases:
1. During writecache storage schema update, it should be flushed with
the old version of node and started clean with a new one.
2. During SSD replacement, to avoid data loss.
Signed-off-by: Evgenii Stratonikov <evgeniy@morphbits.ru>
