Write-Once-Read-Many (WORM) storage promises insurance against litigation by creating an immutable store for fixed content that business units continue to access. Tape and Disk WORM technologies offer effective, high-capacity solutions for both near-at-hand files and long-term archives.

Characteristics of Immutable Storage

"Immutable" literally means "unchangeable." An immutable file-storage solution ensures that the data cannot be modified or deleted after it is written. In order to be practical, immutable solutions must provide the following:

• Speed. An immutable solution designed to meet daily file-access needs must support a high-throughput for both reads and writes. Off-line archival applications may allow for lower speeds, but beware restore-time objectives in SLAs.
• Security. Immutable solutions vary in permanency. For example, filesystem flags can be removed fairly easily to re-expose the file for deletion or editing. While solutions also vary in life-span, the solutions