fsyncUnlock
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Definition
fsyncUnlock
Reduces the lock taken by
fsync
(with the lock option) on amongod
instance by 1.Important
The
fsync
lock
andfsyncUnlock
operations maintain a lock count. Eachfsync
lock
operation increments the lock count, andfsyncUnlock
decrements the lock count.To unlock a
mongod
instance for writes, the lock count must be zero. That is, for a given number offsync
lock
operations, you must issue a corresponding number offsyncUnlock
operations to unlock the instance for writes.fsyncUnlock
is an administrative operation. Typically you will usefsyncUnlock
following a database backup operation.
Syntax
The command has the following syntax:
db.adminCommand( { fsyncUnlock: 1, comment: <any> } )
The comment
field is optional and may contain a comment of any data
type.
Results
The operation returns a document with the following fields:
Field | Description |
---|---|
info | Information on the status of the operation |
lockCount (New in version 3.4) | The number of locks remaining on the instance after the operation. |
ok | The status code. |
Tip
mongosh
provides the helper method
db.fsyncUnlock()
.
Examples
Consider a situation where db.fsyncLock()
has been issued two
times. The following fsyncUnlock
operation reduces the
locks taken by db.fsyncLock()
by 1:
db.adminCommand( { fsyncUnlock: 1 } )
The operation returns the following document:
{ "info" : "fsyncUnlock completed", "lockCount" : NumberLong(1), "ok" : 1 }
As the lockCount
is greater than 0, the mongod
instance
is locked against writes. To unlock the instance for writes, run the
unlock operation again:
db.adminCommand( { fsyncUnlock: 1 } )
The operation returns the following document:
{ "info" : "fsyncUnlock completed", "lockCount" : NumberLong(0), "ok" : 1 }
The mongod
instance is unlocked for writes.