Veritas NetBackup™ Deduplication Guide

UseMemForUpload

If it is set to true, the upload cache directory is mounted in memory as tmpfs. It is especially useful for high speed cloud that disk speed is bottleneck. It can also reduce the disk competition with local LSU. The value is set to true if the system memory is enough.

The default value is true if there is enough memory available.

true

CachePath

The path of the cache. It is created under an MSDP volume according to the space usage of MSDP volumes. It will reserve some space that local LSU cannot write beyond. Usually you do not need to change this path, unless in some case that some volumes are much freer than others, multiple cloud LSUs may be distributed to the same disk volume. For performance consideration, you may need to change this option to make them distributed to different volumes. This path can be changed to reside in a non-MSDP volume.

NA

UploadCacheGB

It is the maximum space usage of upload cache. Upload cache is a subdirectory named "upload" under CachePath. For performance consideration, it should be set to larger than:

(max concurrent write stream number) * MaxFileSizeMB * 2.

So, for 100 concurrent streams, about 13 GB is enough.

12

DownloadDataCacheGB

It is the maximum space usage of data file, mainly the SO BIN file. The larger this cache, the more data files can reside in the cache. Then there is no need to download these files from cloud when doing restore.

500

DownloadMetaCacheGB

It is the maximum space usage of metadata file, mainly the DO file and SO BHD file. The larger this cache, the more meta files can reside in the cache. Then there is no need to download these files from cloud when doing restore.

500

MapCacheGB

It is the max space usage of map file that is used for compatibility of MD5 type fingerprint. The larger this cache, the more map files can reside in the cache.

5

UploadConnNum

Maximum number of concurrent connections to the cloud provider for uploading. Increasing this value is helpful especially for high latency network.

60

DataDownloadConnNum

Maximum number of concurrent connections to the cloud provider for downloading data. Increasing this value is helpful especially for high latency network.

40

MetaDownloadConnNum

Maximum number of concurrent connections to the cloud provider for downloading metadata. Increasing this value is helpful especially for high latency network.

40

MapConnNum

Maximum number of concurrent connections to the cloud provider for downloading map.

40

DeleteConnNum

Maximum number of concurrent connections to the cloud provider for deleting. Increasing this value is helpful especially for high latency network.

100

KeepData

Keep uploaded data to data cache. The value always false if UseMem is true.

false

KeepMeta

Keep uploaded meta to meta cache, always false if UseMem is true.

false

ReadOnly

LSU is read only, cannot write and delete on this LSU.

false

MaxFileSizeMB

Max size of bin file in MB.

64

WriteThreadNum

The number of threads for writing data to the data container in parallel that can improve the performance of IO.

2

RebaseThresholdMB

Rebasing threshold (MB), when image data in container less than the threshold, all of the image data in this container will not be used for deduplication to achieve good locality. Allowed values: 0 to half of MaxFileSizeMB, 0 = disabled

4

CloudDataCacheSize

Default data cache size when adding Cloud LSU.

Decrease this value if enough free space is not available.

500 GiB

CloudMapCacheSize

Default map cache size when adding Cloud LSU.

Decrease this value if enough free space is not available.

5 GiB

CloudMetaCacheSize

Default meta cache size when adding Cloud LSU.

Decrease this value if enough free space is not available.

500 GiB

CloudUploadCacheSize

Default upload cache size when adding Cloud LSU.

The minimum value is 12 GiB.

12 GiB

MaxCloudCacheSize

Specify the maximum cloud cache size in percentage. It is based on total system memory, swap space excluded.

20 %

CloudBits

The number of top-level entries in the cloud cache. This number is (2^CloudBits). Increasing this value improves cache performance, at the expense of extra memory usage. Minimum value = 16, maximum value = 48.

Auto-sized according to MaxCloudCacheSize

DCSCANDownloadTmpPath

While using the dcscan to check cloud LSU, data gets downloaded to this folder. For details, see the dcscan tool in cloud support section.

disabled

UsableMemoryLimit

Specify the maximum usable memory size in percentage.

MaxCacheSize + MaxCloudCacheSize + Cloud in-memory upload cache size must be less than or equal to the value of UsableMemoryLimit

80%

MaxSamplingCacheSize

Specify the maximum sampling cache size in percentage for all cloud LSUs here. UsableMemoryLimit + MaxSamplingCacheSize must be less than or equal to 95%.

By default, each cloud LSU uses 1% memory as sampling cache, so when adding the 6th cloud LSU, the 6th cloud LSU cannot get the memory allocated, we can restart MSDP services to resolve this. When MSDP restarts, all cloud LSUs re-allocate memories equally for sample cache and make sure the total memory usage does not exceed the limit.

We can update 1% default value for each cloud LSU by adding a configuration item LSUSamplingCacheSize under this item.

5%

CloudLSUCheckInterval

The check cloud LSU status interval in seconds.

1800