Backup data is a primary target of ransomware, and legacy backup storage systems expose customers’ last line of defense to the attack. StorONE's S1:Backup works with Veeam, Rubrik, HYCU, Commvault, and others to ensure backup data is immutable to ransomware attacks and extends the value to backup infrastructures while lowering the total cost of ownership. It delivers immutability across all its protocols, including NFS, SMB, S3, iSCSI, Fibre Channel, and NVMe-oF, for ransomware resiliency. The S1 captures every backup job into an immutable state, retains immutable copies indefinitely without impacting performance, and roll back to a 30-second-old immutable copy if attacked. It features auto-tiering between a generous flash tier and up to a 15-plus PB hard-disk tier to support hundreds of simultaneous backup jobs per hour for low RPO. The S1 can scale to 15-plus PBs in a single cluster for long-term data retention while delivering high-performance backup and recovery. The backup storage system recovers from an 18-TB drive failure in two hours, employs a unique bit-error-rot protection for long-term retention, and offers flexibility to mix new drive densities without creating new volumes or reconfiguring backup jobs.