Which factor(s) impacts the Dell Avamar checkpoint overhead?

Checkpoint overhead is the amount of storage space required to maintain a consistent point-in-time map of the data on the Avamar grid. The primary factor impacting this overhead is the system's daily change rate. A higher change rate means more new data chunks are added and more existing chunks are referenced or dereferenced between checkpoints. This results in a larger volume of metadata changes that must be recorded in the new checkpoint, thereby increasing its size and the associated storage overhead.

B. Frequency of client backups: This can influence the change rate, but the change rate itself is the direct factor. Frequent backups of static data would have minimal impact.
C. Whether backups succeed everyday: Failed backups would lead to a lower change rate for that day, thus decreasing the checkpoint overhead, but the rate of change is the fundamental driver.
D. Size of the grid and licensed amount: A larger grid has more capacity for overhead, but the actual overhead generated is a function of data churn (change rate), not the system's physical or licensed size.

1. Dell Avamar System Administration Guide 19.7, Page 113, "Checkpoints": "A checkpoint is a consistent, point-in-time view of the entire set of data on the GSAN... The amount of space that checkpoints consume is proportional to the daily rate of data change on the Avamar server."

2. Dell Avamar Technical and Architectural Deep Dive (White Paper), "Avamar Architecture" section: The document explains that checkpoints record the state of stripes. The number of new or modified stripes is directly related to the amount of new, changed data ingested since the last checkpoint.