Data Integrity

Among the most important components of any file system are data integrity and security, something not found in most legacy storage systems. One major differentiator of ZFS from other file systems is that ZFS is designed with an emphasis on data integrity―data protection against silent data corruption issues, generally not detectable by hardware RAID controllers. Examples of corruption can be;

• Bit Rot
• Phantom Writes 
• Misdirected Reads and Writes
• DMA Parity Errors
• Duplicate Software
• Driver Bugs
• Accidental Overwrites
• Malicious Tampering
• Boot Storm Issues
• Electro-Magnetic Pulses

For ZFS, data integrity is achieved by using end-to-end checksumming and transactional copy-on-write to prevent silent data corruption throughout the entire file system tree. Each block of data is checksummed and the checksum value is then saved in the pointer to that block—rather than at the actual block itself. This checksumming continues all the way up the file system's data hierarchy to the root node, which is also checksummed, thus creating what’s known as a Merkle tree. When a given block is read, its checksum is calculated and compared to the checksum stored in its parent block pointer.

ZFS uses these end-to-end checksums to detect and combat silent data corruption. If a disk returns bad data, ZFS detects it and retries the read. If the values do not match and is part of a mirror or RAID-Z group, ZFS will self-heal by using the checksum to determine which copy is correct, provide good data to the application, and repair the damaged copy.

End-to-end data integrity, as found in NexentaStor, doesn't require any special hardware. There is no need to acquire proprietary hardware, and you don't need to reformat drives with into special sectors or have to modify applications to benefit from it. The bullet-proof data integrity and automatic self-healing is an inherent feature found within ZFS, and it works with any mixture of hybrid storage.

Data corruption is significant concern for any storage administrator. As exponential storage growth continues, the threat of data degradation over time is an inevitable reality and potentially business crippling. Incorporating highly reliable data replication and retention solutions becomes mission critical for every organization. Verifying data reliability through checksumming should be mandatory.

ZFS clearly protects data better than typical legacy storage options. Choosing a robust data storage solution is a daunting task in itself without the added concern for protection against data corruption. No other data storage solution offers the same level of bullet-proof data integrity as a ZFS Software-defined Storage solution like NexentaStor.