The Cache Repository is new function, introduced in Veeam Backup & Replication v10. It is used for NAS backup only and it is crucial in incremental backup. It also the controlling uinit of a NAS backup job.
Whenever a NAS backup job runs, it is the Cache Repository that requests the File Proxy to retrieve data from the source share. The File Proxy then sends back the top level structure hash’s. The cache repository places them into RAM and initiate a CRC check on the data stored in the vcache (generated with the previous job run). If there is a match with the vcache, no file have to be processed and the File Proxy will be instructed to iterate and repeat at a deeper level of the share to find the next folder with a mismatch.
There can be only one Cache Repository per source share.
Ideally, the Cache Repository should sit as near as possible to the File Proxy and source data: the bigger the share, the more the traffic between File Proxies and Cache Repository. At the best, they should be one hop away from each other.
No disk sizing is required: usually the size of the vcache files does not exceed 4 GB and due to the optimized size of the cache, data will be loaded into memory when needed. This also makes fast disks not necessary.
The Cache Repository should not be part of a Scale-out Backup Repository as there will be no befinits in distributing its content into multiple exentents. Also, the capacity tier (if any) would be ignored anyway.
As far as compute resources are concerned, we recommend a minimum of 2 cores and 8 GB of memory.