Question & Answer
Question
How to use nzbackup argument FSYNC_DEST_BYTES
Cause
FSYNC_DEST_BYTES is a Netezza file system backup connector option that throttles the host writes to an external file system by flushing the modified buffers after a specified number of bytes and waiting for the device to finish.
This option helps to reduce incidents where the NPS host restarts of fails over while writing data to a slow external file system.
Answer
You use the FSYNC_DEST_BYTES option to set the maximum amount of data that will be buffered before flushing to the destination drive. For example:
Note that using this option may increase the overall time of the backup process, so you don't have to use this option unless file system backups are causing your NPS host to freeze, restart or failover.
How to choose the best value for your backup operation?
There are no default values and you must try them to value the impact on the backup operations. These are the points to consider.
nzbackup -dir /home/user/backups -u user -pw password -db mydb -connectorArgs FSYNC_DEST_BYTES=2147483648
Note that using this option may increase the overall time of the backup process, so you don't have to use this option unless file system backups are causing your NPS host to freeze, restart or failover.
How to choose the best value for your backup operation?
There are no default values and you must try them to value the impact on the backup operations. These are the points to consider.
- Start by using sync every 2-4GB (2147483648 - 4294967296)
- If you decrease the value of the parameter, the synching mechanism will be called with less bytes. Smaller writes means more of them, and that will increase the the overall backup time.
- If you increase the value of the parameter, the backup time may slightly decrease, but the restart or failover problem might appear during the backup process.
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Document Information
Modified date:
04 September 2023
UID
ibm17030529