DR Series Software 4.0.3 - Command Line Reference Guide

About Data Check

The purpose of the Data Check feature is to perform data integrity checks to detect potential silent data inconsistencies that can affect the DR Series system disks or disk subsystems, and protect user data before there is any potential data loss.

Silent data inconsistencies can be any of the following types of disk-based data storage issues: hardware imperfections, bit rot, current spikes, disk firmware problems, and ghost writes. Data Check performs its own integral data integrity checks that detect and identify potential issues after performing the following scans:

For more information, see Continuous Data Verification Scans and Priority Write Verify Scans.

Priority Write Verify Scans

Data Check performs an early write verify scan, also known as a namespace scan, when files are first created or when they are modified by users. All of the modified files are flagged for priority scanning and this process is based on its timestamp—with a higher priority given to the most recently modified files. Early write verify scans are performed every five minutes when the other DR Series system operations are idle. For more information, see About Data Check and Continuous Data Verification Scans.

Continuous Data Verification Scans

Data Check performs a data verification scan, also known as a blockmap scan, which cycles every two hours through all of the objects in the data store. Data integrity verification is done by recalculating the hash values for the underlying data, and comparing these to the stored hash values using an additional checksum process. Any unexpected data inconsistencies are reported using the DR Series system alerts process.

For more information, see About Data Check and Priority Write Verify Scans.

Data Check CLI Commands

These DR Series system CLI commands allow you to perform the following Data Check-related scans and display current Data Check status. There are two sets of Data Check related DR Series system CLI commands: system --datacheck and stats --datacheck.

system --datacheck Commands

stats --datacheck Commands