Optimizing CPU and memory usage in NetBackup Direct-IO
The Direct-IO plugin allows high-bandwidth backups while offering control over system resource usage. By tuning specific configuration parameters, administrators can manage CPU and memory consumption per backup job, especially useful in resource-constrained environments.
To control how much CPU each backup job consumes, adjust the maxConcurrentWrites parameter. The following table summarizes how this parameter affects CPU usage:
Table:
Parameter | Description |
|---|---|
maxConcurrentWrites | Controls the number of concurrent write operations per backup job.
|
The following parameters control memory allocation during the write operations:
Table:
Parameter | Description |
|---|---|
maxWriteBufferSizeMB | Specifies the maximum size of the write buffer. This buffer temporarily holds data before it is written to the storage backend. Allowed values: 1 - 2000 MB Default: 512 MB |
maxPendingWriteDataSizeMB | Defines the maximum amount of data that can be queued in memory before being added to the write buffer. Allowed values: 1 - 1000 MB Default: 128 MB |
Configuration example:
/usr/openv/lib/ost-plugins/spanfs.conf
{
"writeParams": {
"maxWriteBufferSizeMB": 512,
"maxPendingWriteDataSizeMB": 128
}
}
To estimate the total memory usage for write operations, use the following formula:
Total memory usage (MB) = maxWriteBufferSizeMB + maxPendingWriteDataSizeMB
For example, with the above configuration, total memory usage = 512 + 128 = 640 MB
This value represents the peak memory that may be consumed during intensive write operations. It is recommended to adjust these values based on available system memory and workload characteristics.
While these configuration changes help conserve system resources, they may also affect backup performance. Consider the following tradeoffs when applying these settings:
Lower resource usage typically results in longer backup times.
These settings are best suited for environments where minimizing CPU and memory usage is more critical than backup speed.