Tag Archives: Backup

Failed to assign Veeam Data Cloud Vault with the storage account

Veeam NAS Sizing – Cache Repositories and Metadata

For those diving into NAS sizing, I wanted to share this write up to help explain the roles of the Cache Repositories and Metadata. The sizing of these components varies depending on the type of backup storage you’re using. This consideration has become increasingly important with the addition of object storage support in v12.

A Cache Repository is a storage location where Veeam Backup & Replication keeps temporary cached metadata (folder level hashes) for the NAS data being protected. A Cache Repository improves incremental backup performance because it enables Veeam to quickly identify source folders that don’t have any changes via matching hashes stored in the Cache Repository.

When NAS backup is targeting a disk-based repository, the cache metadata is held in memory so very little if any storage on the Cache Repository is required, roughly 1 to 2 GB for disk-based repositories.

Not to be confused with cached metadata (folder level hashes) on the Cache Repository, Metadata is created by Veeam used to describe the backup files, source, files name version and pointers to backup blobs. Most often, when performing restore, merge, transform operations, Veeam interacts with this Metadata rather than with the backup data.

Metadata is always redundant (“meta” and “metabackup” or “metacopyv2”). The actual placement and number of metadata copies is dependent on the repository configuration and type. This is important to understand because the number and placement of Metadata will impact how much storage is required.

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Changing Data Compression and Deduplication settings

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So you probably already knew that you can change compression and deduplication settings for existing backup jobs, the new settings will not have any effect on previously created backup files in the chain. They will be applied to new backup files after the settings were created.

For deduplication, the changes take effect after you create an active full backup.

For Compression, the change takes effect to the very next backup files created.

Something that you may not have known is that if you use the reverse incremental backup method, the newly created backup files will contain a mixture of data blocks compressed at different levels.

Let’s say, you are backing up using reverse incremental with the compression set to ‘None’. After several job sessions, you wish to increase the compression by changing from ‘None’ to ‘Optimal’. Now, for reverse incremental backup chains, the full backup file is rebuilt with every job session to include new data blocks. As a result, the full backup file will contain a mixture of data blocks: data blocks compressed at the ‘None’ level and data blocks compressed at the ‘Optimal’ level.

If you want the newly created backup file to contain data blocks compressed at one level, you can create an active full backup. An active full backup will consist of retrieving all the data for the whole VM image from the production infrastructure and compress it at the new compression level. All subsequent backup files in the backup chain will also use the new compression level.

For space-saving goodness, I recommend checking out ReFS and how Veeam can leverage it, you can learn more about ReFS here https://hyperv.veeam.com/blog/benefits-of-refs-file-system-in-windows-server-2016/