NFS ObjectStore Disk Cache Size Guidelines

Proper sizing of the cache is extremely important so that all configured Object Stores work seamlessly.

If the cache lacks space, NFS clients can get NO Space errors. When the software writes data to the ObjectStore, it is temporarily stored in the disk cache while the backup runs in another thread. After the software backs up the data and the chunk in which it is written is committed, it becomes available for pruning. In order to account for this operation, the disk cache must be large enough to store any burst of data that is written faster than it can be backed up. However, it can be difficult to forecast the size of burst data. We recommend that the cache is large enough for at least one day's worth of new written data. Additional space is beneficial for improving performance when reading data and for overwriting existing data. We also recommend that the cache size be at least 1TB.