In a fully-populated Data Protection Group (DPG) with sufficient capacity, how many disk drives need to fail sequentially to stop the XtremlO X2 data services?

XtremIO X2 utilizes XtremIO Data Protection (XDP), a proprietary, flash-specific, dual-parity data protection algorithm. Unlike traditional RAID, XDP offers significantly higher resilience. In a fully populated Data Protection Group (DPG), which corresponds to a fully populated X-Brick, XDP is designed to maintain data availability and continue operating through up to eight concurrent SSD failures. The failure of a ninth drive would exceed the algorithm's ability to reconstruct the data from the remaining data and parity strips, resulting in data loss and the subsequent stoppage of data services for the array.

A. 6: This is incorrect. While XDP can tolerate six failures, its maximum tolerance in a fully populated DPG is higher before data services are stopped.
B. 7: This is incorrect. The system can sustain seven concurrent failures and remain operational, although performance would be in a degraded state.
C. 2: This is incorrect. Two failures is the tolerance limit for traditional dual-parity RAID (like RAID 6) or the limit for XDP to rebuild with no performance impact, but XDP can tolerate many more failures before data becomes unavailable.

1. Dell EMC XtremIO X2 with XtremIO Data Protection (XDP) - A Detailed Review (White Paper), April 2019.

Page 10, Section: XDP Reliability: "XDP can withstand up to eight concurrent SSD failures in a 72-SSD X-Brick without data loss." (A fully populated DPG in an X2 system can have up to 72 SSDs). This directly supports that the 9th failure would cause data loss.

2. Dell EMC XtremIO X2 Storage Array Architecture (White Paper), August 2017.

Page 21, Section: XtremIO Data Protection (XDP): "XDP is a powerful wide-striping protection algorithm that protects the system from up to eight drive failures, while delivering extreme performance, and up to 100% storage efficiency." This confirms the 8-drive failure tolerance, implying the 9th failure is catastrophic.