Vault 2015 Notes: First Day Morning

After surviving the morning commute, I found myself 10 minutes late for the first talk.

The first talk was a joint topic on different aspects of the future and current storage system: Persistent Memory, Multiqueue (mentioned new IO scheduler), SMR, SCSI queue tree (better maintenance), LIO/SCST merger, iSCSI performance reconciling multiqueue and multi-connection conflicts by proposing new IETF iSCSI extension for Linux, kernel Rescan.

Second topic from SanDisk is about Data Center architectures. I came into a revelation that the Data Centers were consolidated into different resource poolings and scaling granularity.   As I reckoned the recent industry consolidation: Avago’s big acquistions making it relevant as a fabrics provider, SanDisk’s ascend into Enterprise storage was also leapfrogging, and multiple storage vendors had acquired some sorts of data management outfits (Pentaho/HDS for instance). This topic reviewed heterogeneous replication (one on SSD, more on HDD), erasure coding on Flash. SanDisk’s contributions/patches to Ceph and NoSQL improved performance by several X’s, future reducing price/performance gap.

Next session in Brfs was interesting, though I lost most part of it due to limited seating in the room. I vaguely remembered Chris was excited about CRC verification, improved scrub code, upcoming inline dedup, sub-volume quota, and new tests that made critical issues consistently reproducible, less write amplification using RocksDB, etc. I also had a good time learning how Facebook used and improved Glusterfs.

The pNFS talk was most about the basics but Christopher did attract my attention when he mentioned using SCSI3 reservation for fencing during error handling, and mentioned the projects/products I worked on before.  His then went to explain how his new pNFS server was structured and coded. The server used XFS and heavily reused the existing code base (like direct IO, no separate layout modules, etc). The performance was said to be linearly scaled.  And yes, he did mentioned omission of small files through pNFS protocol. The source code is kernel 4.0


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