How to choose: answering the main questions
How much storage is needed for backups?
Rule: total protected data volume × 3–4 with a 30-day retention period including increments. Veeam/PBS deduplication compresses virtual machines by 2–4 times, so a chassis with 4–8 drives of 8–12 TB each covers small and medium business infrastructure with room to grow for years.
Which RAID and drives should you choose?
RAID6 on enterprise-grade HDDs: survives a two-drive failure, and write speeds are sufficient for overnight tasks. SSDs are only needed for the deduplication database and catalog. A separate volume or removable media for offline backups is essential to protect against ransomware.
Is a refurbished server sufficient?
Backup is an ideal use case for refurbished hardware: the workload is nocturnal and sequential. A Dell R540/R740xd or HPE DL380 Gen10 with a large drive bay will cost 40–60% less than new units while delivering the same performance.