Most customers back up their data after business hours because the backup operation does not compete with performance sensitive protocol like SMB and NFS user activity. NDMP backup and restore performance are highly dependent upon many factors, such as the NDMP backup models, network bandwidth, DMA configuration, available system resources, directory depth, number of files per directory, and file size.
The following considerations and best practices can help you optimize OneFS NDMP backup and restore operations.
- Install the latest roll up patches (RUP) for OneFS and DMA. We strongly recommend installing OneFS 8.2.2 GA RUP 2021-09 or better Patch and OneFS 9.1.0.14+ when using OneFS NDMP.
- Run a maximum of eight NDMP concurrent sessions for each Fibre attached storage node. Run four NDMP concurrent sessions for each PowerScale backup accelerator node to obtain optimal throughput in each session.
- Isolate NDMP backup sessions from other workloads such as SMB or NFS user activity.
- For NDMP two-way backups, the B100 backup accelerator requires OneFS 9.3.0.0 or later.
- Assign static IP addresses to Fibre Attached Storage nodes. Attach more Fibre Attached Storage nodes to larger PowerScale clusters or if you are backing up to more tape devices. The following table shows the recommendation of PowerScale nodes for each Fibre attached storage node.
Table 4. Recommended PowerScale nodes for each Fibre attached storage node
F-Series |
3 |
H-Series |
3 |
A-Series |
3 |
X-Series |
3 |
NL-Series |
3 |
S-Series |
3 |
HD-Series |
3 |
- NDMP backups result in high Recovery Point Objectives (RPOs) and Recovery Time Objectives (RTOs). You can attach one or more Fibre Attached Storage nodes to the PowerScale cluster before running NDMP two-way sessions and reduce the RPO and RTO.
- NDMP backup and restore performance depends on the file size. The performance is considerably reduced for small files. If you are backing up large numbers of small files, set up a separate schedule for each directory.
- If you restore files to another PowerScale cluster using NDMP, have the same OneFS and patch version installed on the source and target clusters.
- If you are performing NDMP three-way backups, run multiple NDMP sessions on multiple nodes in the PowerScale cluster.
- For NDMP three-way backups, configure using dedicated switch ports for all NDMP PowerScale nodes.
- Use Dell EMC PowerScale SmartPools and file pool policies to move data to a node pool for NDMP backups.
- With NDMP, compressed chunks is decompressed, each file is then reassembled and sent over Fibre Channel (2-way NDMP) or Ethernet (3-way NDMP) in uncompressed form to the backup devices.
- With NDMP, deduplicated data is rehydrated when it leaves the cluster, and shadow stores and shadow links are not preserved on the backup. The NDMP tape device or VTL will need to have sufficient space to house the full size of the dataset.
- Recover files through DDAR if you recover large numbers of files frequently.
- Use the largest tape block size available for OneFS to increase NDMP backup and restore throughput.
- If possible, do not include or exclude files from NDMP backups. Including or excluding files can affect backup performance, due to filtering overhead.
- Limit the depth of nested subdirectories in OneFS file system for NDMP backups.
- Enable parallelism on DMA to enable multi-stream backup if DMA supports this option, and ensure that there are enough tape devices to support the multi-stream backup. This feature allows OneFS NDMP to back up data to multiple tape devices simultaneously and improves the backup performance.
- Consider the following NDMP limitations when using NDMP backups.
- NDMP supports block sizes up to 512 KB.
- NDMP does not support more than 4 KB file path length.
- NDMP does not back up OneFS configuration data, such as file protection level policies and quotas.
- NDMP does not support recovering data from a file system other than OneFS.
- Fibre Attached Storage nodes cannot interact with more than 4096 tape paths.
- The maximum length of the FILESYSTEM NDMP environment variable supported for a backup operation is 1024.