- Troubleshooting >
- Backup
Backup¶
Logs Display MongodVersionException
¶
The MongodVersionException
can occur if the
Backup Daemon’s host cannot access the
internet to download the version or versions of MongoDB required
for the backed-up databases. Each database requires a version of
MongoDB that matches the database’s version. Specifically, for each
instance you must run the latest stable release of that release
series.
If the Daemon runs without access to the internet, you must manually download the required MongoDB versions, as described here:
Go to the MongoDB downloads page and download the appropriate versions for your environment.
Copy the download to the Daemon’s host.
Decompress the download into the directory specified in the
mongodb.release.directory
setting in the Daemon’sconf-daemon.properties
file. To learn the file’s location, see Ops Manager Configuration Settings.Within the directory specified in the
mongodb.release.directory
setting, the folder structure for MongoDB should look like the following:
Insufficient Oplog Size Error¶
When using the Ops Manager interface to back up a MongoDB cluster, Ops Manager checks to see if the cluster’s oplogs are, based on their recent usage, large enough to hold a minimum of 3 hours worth of data based on the last 24 hours of usage patterns. If the oplogs are not large enough, it may be possible that the oplogs may have turned over multiple times, creating a gap between where a backup ends and an oplog starts.
If the oplog size check fails, the user cannot enable backups and is shown the warning:
Warning
Insufficient oplog size: The oplog window must be at least 3 hours over the last 24 hours for all members of replica set <name>. Please increase the oplog.
If possible, wait to start a backup until the oplog has had sufficient time to meet the size requirement.
If this is not possible, the minimum oplog size value can be
changed. See mms.backup.minimumOplogWindowHours
for how
to set this value.
Warning
Do not change the minimum oplog size unless you are certain smaller backups still provide useful backups.
Important
MongoDB recommends only changing this value temporarily to permit a test backup job to execute. The minimum oplog size value should be reset to the default as soon as possible. If an oplog is set to too small of a value, it can result in a gap between a backup job and an oplog which makes the backup unusuable for restores. Stale backup jobs must be resynchronized before it can be used for restores.
Understanding the risks given, you can start backups using this changed minimum value. Once you pass the 24 hour mark, you should reset this minimum value to preserve the sanity check for the global Ops Manager installation going forward.