Storage Area Network

March 18, 2020, 10:40 a.m. by lufy

As a linux OS tester, when handling with adaptation test, storaege is often mentioned. I often confused of this. Here is a description of SAN and NAS, from https://www.netapp.com/us/info/what-is-storage-area-network.aspx. It's a lot help to me.

Storage area networks (SANs) are the most common storage networking architecture used by enterprises for business-critical applications that need to deliver high throughput and low latency. A rapidly growing portion of SAN deployments leverages all-flash storage to gain its high performance, consistent low latency, and lower total cost when compared to spinning disk. By storing data in centralized shared storage, SANs enable organizations to apply consistent methodologies and tools for security, data protection, and disaster recovery.

A SAN is block-based storage, leveraging a high-speed architecture that connects servers to their logical disk units (LUNs). A LUN is a range of blocks provisioned from a pool of shared storage and presented to the server as a logical disk. The server partitions and formats those blocks—typically with a file system—so that it can store data on the LUN just as it would on local disk storage.

SANs make up about two-thirds of the total networked storage market. They are designed to remove single points of failure, making SANs highly available and resilient. A well-designed SAN can easily withstand multiple component or device failures.

SAN Use Cases

Storage area networks are frequently deployed in support of business-critical, performance-sensitive applications such as:

Oracle databases. These are frequently business-critical and require the highest performance and availability.
Microsoft SQL Server databases. Like Oracle databases, MS SQL Server databases commonly store an enterprise’s most valuable data, so they require the highest performance and availability.
Large virtualization deployments using VMware, KVM, or Microsoft Hyper-V. These environments often extend to thousands of virtual machines running a broad range of operating systems and applications, with different performance requirements. Virtualized environments concentrate many applications, so infrastructure reliability becomes even more important because a failure can cause multiple application outages.
Large virtual desktop infrastructures (VDIs). These environments serve virtual desktops to large numbers of an organization’s users. Some VDI environments can easily number in the tens of thousands of virtual desktops. By centralizing the virtual desktops, organizations can more easily manage data protection and data security.
SAP or other large ERP or CRM environments. SAN architectures are ideal for enterprise resource planning and customer resource management workloads.

Types of SAN

The most common SAN protocols are:

Fibre Channel Protocol (FCP). The most widely used SAN or block protocol, deployed in 70% to 80% of the total SAN market. FCP uses Fibre Channel transport protocols with embedded SCSI commands.
Internet Small Computer System Interface (iSCSI). The next largest SAN or block protocol, with approximately 10% to 15% of the market. iSCSI encapsulates SCSI commands inside an Ethernet frame and then uses an IP Ethernet network for transport.
Fibre Channel over Ethernet (FCoE). FCoE is less than 5% of the SAN market place. It is similar to iSCSI, since it encapsulates an FC frame inside an Ethernet datagram. Then like iSCSI, it uses an IP Ethernet network for transport.
Non-Volatile Memory Express over Fibre Channel (FC-NVMe). NVMe is an interface protocol for accessing flash storage via a PCI Express (PCIe) bus. Unlike traditional all-flash architectures, which are limited to a single, serial command queue, NVMe supports tens of thousands of parallel queues, each with the ability to support tens of thousands of concurrent commands.

SAN vs. NAS

Both SAN and network-attached storage (NAS) are methods of managing storage centrally and sharing that storage with multiple hosts (servers). However, NAS is Ethernet-based, while SAN can use Ethernet and Fibre Channel. In addition, while SAN focuses on high performance and low latency, NAS focuses on ease of use, manageability, scalability, and lower total cost of ownership (TCO). Unlike SAN, NAS storage controllers partition the storage and then own the file system. Effectively this makes a NAS server look like a Windows or UNIX/Linux server to the server consuming the storage.

SAN Protocols:

Fibre Channel Protocol (FCP)
Internet Small Computer System Interface (iSCSI)
Fibre Channel over Ethernet (FCoE)
Non-Volatile Memory Express over Fibre Channel (FC-NVMe)

NAS Protocols:

Common Internet File Services / Server Message Block (CIFS/SMB). This is the protocol that Windows usually uses.
Network File System (NFS). NFS was first developed for use with UNIX servers and is also a common Linux protocol.

NetApp and SAN

NetApp is now the fastest growing enterprise SAN storage vendor^[1]:

Accelerate your SAN solutions with NetApp’s leading performance^[2]
Leverage the best cloud-connected infrastructure to flexibly move and protect your data across your hybrid cloud environment
Deliver the high availability (greater than six nines) that your business applications require
Reduce your management costs and TCO

NetApp® SAN solutions have leading capabilities for running your business-critical applications. NetApp works closely with Brocade to deliver innovative storage networking solutions that help reduce complexity and cost while enabling maximum performance with consistent low latency to increase business agility

Brocade’s FC SAN solutions deliver a reliable, scalable, and high-performance foundation for storage networks.
Brocade’s industry-leading FC technology and innovation ease the transition to NVMe-capable SAN.
NetApp was first to support Brocade’s ground-breaking 32Gb technology, enabling ultrafast connectivity and performance for your SAN.

Learn more about flash storage and how it can accelerate your SAN solutions.

[1]: Source: IDC, WW Quarterly Enterprise Storage Systems Tracker 2017Q4, March 1, 2018
[2]: The AFF A700s achieved 2,400,059.26 SPC-1 IOPS at an average response time of 0.69 milliseconds. It is the top-performing enterprise all-flash array among the major storage providers and in the top three overall on the SPC-1 Performance list.

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