The issue was related to “max_sectors_kb” value on Linux. I think that EMC should add recommendation value to best practices or connectivity guide for EMC Unity. Also read my blog post about that: I/O Block Size Best Practice on EMC All Flash/Hybrid Flash Array and Linux (Physical And Virtual) - Davoud Teimouri - Virtualization and Data Center
We have some Unity XT 880F that the storage arrays are serving to some Oracle databases. Sometimes, we saw high Read/Write Cache Miss on the storage arrays and very large I/O block size. This situation is cause of high service time, high response time and latency of LUN. Why the arrays are applying I/O on disks directly and didn't use SP Cache? There is no issue on storage array but latency is too high on All Flash Storage!
High Read/Write Cache Miss Hit on All Flash Array