HP D2D D2D NAS Integration with CommVault (EH985-90934, March 2011) - Page 20
Device Streams, Allocate, number of writers, Enable Stream Randomization
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Device Streams: Device streams must be spread across the number of storage policies that could run simultaneously to CommVaultShare1. In this case we plan to have only one storage policy to CommVaultShare1, so we can allocate 12 streams. What this means is that we could back up 12 hosts simultaneously to CommVaultShare 1 by setting Device Streams (General tab) and Allocate number of writers (Mount Paths tab) to 12. Do not check Enable Stream Randomization because this will disrupt the deduplication efficiency of the HP D2D NAS share. NOTE: If you are backing up multiple hosts, you may like to create separate folders for each host within the CommVaultShare1 library. Use Windows Explorer to do this. Setting the Container/Chunk size When using D2D NAS the CommVault backup software allocates a size to the containers (Chunks in CommVault terminology) where the user data files will be stored on the Disk Library. The size of these containers can be changed. D2D NAS has a fixed limit of 25000 files, so the larger we make the containers the more data we can hold on the D2D NAS share. Ideally, the bigger the containers the better as it stops us hitting the 25000 file limit and reduces fragmentation in the backup. Set the container (chunk) size as follows: 1. Select the Storage Policy that we have just created and double click the storage policy in the right-hand navigation window to get the Copy Properties window. 2. Click on the Data Paths tab in the Copy Properties window AND select the path. 3. Now click the Properties button at the bottom of the data paths page as shown below Edit the Chunk size (MB) section to use a specific value and click OK. In this case we will change the chunk size from 2048 (default) to 4096. The maximum chunk size is 32 GB, but this can lead to some performance impact so typically a choice of 16 GB chunk size is a good compromise. 20 Discover the NAS CIFS share in CommVault