Fibre Channel Protocol in a Zero Trust world

Fibre Channel SANs (storage area networks) are touted as more secure than IP-based storage networks. In a way, that is true because Fibre Channel is a distinct network separated from the mainstream client-based applications. Moreover, the Fibre Channel protocol is entirely different from IP, and the deep understanding of the protocol, its implementations are exclusive to a selected cohort of practitioners and professionals in the storage technology industry.

The data landscape has changed significantly compared to the days where FC SANs were dominating the enterprise. The era was the mid 90s and early 2000s. EMC® was king; IBM® Shark was a top-tier predator; NetApp® was just getting over its WAFL™ NAS overdose to jump into Fibre Channel. There were other fishes in the Fibre Channel sea.

But the sands of storage networking have been shifting. Today, data is at the center of the universe. Data is the prized possession of every organization, and has also become the most coveted prize for data thieves, threat actors and other malefactors in the digital world. The Fibre Channel protocol has been changing too, under its revised specifications and implementations through its newer iterations in the past decade. This change in advancement of Fibre Channel as a storage networking protocol is less often mentioned, but nevertheless vital in the shift of the Fibre Channel SANs into a Zero Trust world.

Zones, masks and maps

Many storage practitioners are familiar with the type of security measures employed by Fibre Channel in the yesteryears. And this still rings true in many of the FC SANs that we know of today. For specific devices to connect to each other, from hosts to the storage LUNs (logical unit numbers), FC zoning must be configured. This could be hard zoning or soft zoning, where the concept involves segmentation and the grouping of configured FC ports of both the ends to “see” each other and to communicate, facilitated by the FC switches. These ports are either the initiators or the storage target, each with its own unique WWN (World Wide Name).

On top of zoning, storage practitioners also configure LUN masking at the host side, where only certain assigned LUNs from the storage array is “exposed” to the specific host initiators. In conjunction, at the storage array side, the LUNs are also associated to only a group of host initiators that are allowed to connect to the selected LUNs. This is the LUN mapping part.

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Crash consistent data recovery for ZFS volumes

While TrueNAS® CORE and TrueNAS® Enterprise are more well known for its NAS (network attached storage) prowess, many organizations are also confidently placing their enterprise applications such as hypervisors and databases on TrueNAS® via SANs (storage area networks) as well. Both iSCSI and Fibre Channel™ (selected TrueNAS® Enterprise storage models) protocols are supported well.

To reliably protect these block-based applications via the SAN protocols, ZFS snapshot is the key technology that can be dependent upon to restore the enterprise applications quickly. However, there are still some confusions when it comes to the state of recovery from the ZFS snapshots. On that matter, this situations are not unique to the ZFS environments because as with many other storage technologies, the confusion often stem from the (mis)understanding of the consistency state of the data in the backups and in the snapshots.

Crash Consistency vs Application Consistency

To dispel this misunderstanding, we must first begin with the understanding of a generic filesystem agnostic snapshot. It is a point-in-time copy, just like a data copy on the tape or in the disks or in the cloud backup. It is a complete image of the data and the state of the data at the storage layer at the time the storage snapshot was taken. This means that the data and metadata in this snapshot copy/version has a consistent state at that point in time. This state is frozen for this particular snapshot version, and therefore it is often labeled as “crash consistent“.

In the event of a subsystem (application, compute, storage, rack, site, etc) failure or a power loss, data recovery can be initiated using the last known “crash consistent” state, i.e. restoring from the last good backup or snapshot copy. Depending on applications, operating systems, hypervisors, filesystems and the subsystems (journals, transaction logs, protocol resiliency primitives etc) that are aligned with them, some workloads will just continue from where it stopped. It may already have some recovery mechanisms or these workloads can accept data loss without data corruption and inconsistencies.

Some applications, especially databases, are more sensitive to data and state consistencies. That is because of how these applications are designed. Take for instance, the Oracle® database. When an Oracle® database instance is online, there is an SGA (system global area) which handles all the running mechanics of the database. SGA exists in the memory of the compute along with transaction logs, tablespaces, and open files that represent the Oracle® database instance. From time to time, often measured in seconds, the state of the Oracle® instance and the data it is processing have to be synched to non-volatile, persistent storage. This commit is important to ensure the integrity of the data at all times.

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The future of Fibre Channel in the Cloud Era

The world has pretty much settled that hybrid cloud is the way to go for IT infrastructure services today. Straddled between the enterprise data center and the infrastructure-as-a-service in public cloud offerings, hybrid clouds define the storage ecosystems and architecture of choice.

A recent Blocks & Files article, “Broadcom server-storage connectivity sales down but recovery coming” caught my attention. One segment mentioned that the server-storage connectivity sales was down 9% leading me to think “Is this a blip or is it a signal that Fibre Channel, the venerable SAN (storage area network) protocol is on the wane?

Fibre Channel Sign

Thus, I am pondering the position of Fibre Channel SANs in the cloud era. Where does it stand now and in the near future? Continue reading