`Degraded` mode is set automatically after error counter is over the
threshold. `ReadOnly` mode can still be set by an administrator.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
It was added back in 2fb379b7 when we had many shard modes. Now we have
only two and comments for constants are rather descriptive.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
In read-only mode modifying operations are immediately returned with
error and all background operations are suspended.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
Provide shard mode information via `DumpInfo()`. Delete atomic field from
Shard structure since it duplicates new field.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Shard's mode was not used in the Node, so added only two modes whose roles
are clear. More modes will be added in the future.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
