Storage Area Network (SAN) is a dedicated high-speed network that provides access to block level storage. SANs are primarily used to make storage devices accessible to servers so that the devices appear like locally attached devices to the operating system. SAN typically uses Fibre Channel protocol, though SANs using iSCSI protocol are also common.
What are the benefits of SAN?
Here are some of the key benefits of using a SAN:
- Centralized storage – SAN provides a centralized pool of storage that can be accessed by multiple servers.
- Scalability – It is easy to scale SAN storage as requirements grow by simply adding more storage to the SAN.
- Availability – SAN provides multiple redundant components like dual fabrics, controllers etc. which makes it highly available.
- Better resource utilization – With SAN, multiple servers can share the same storage pool leading to better utilization of storage resources.
- Advanced features – SAN storage provides advanced features like thin provisioning, deduplication, snapshots etc.
- Disaster recovery – SAN replication makes it easier to have disaster recovery solutions.
- Data mobility – Data can be moved between servers without any disruption to users.
- No distance limitations – SAN allows servers and storage to be at long distances from each other.
What are the components of a SAN?
Following are the key components that make up a typical SAN architecture:
- Servers (Hosts) – The servers or hosts connect to the SAN to access shared storage. They use SAN protocols like Fibre Channel, iSCSI etc. to communicate with the storage.
- SAN Switches – SAN switches create a dedicated storage network. They provide high speed switching fabric to interconnect servers and storage.
- Storage Devices – The storage devices provide block-level storage that is accessible over the SAN. Disk arrays, JBODs etc. are common storage devices.
- HBA/CNA Cards – Host bus adapter (HBA) cards or converged network adapter (CNA) cards provide ports for servers to connect to SAN switches.
- Cables – Cables like fiber optic cables connect the various SAN components.
- SAN Management Software – Management software is used to configure, monitor and manage different elements of a SAN.
What are the key SAN protocols?
The main protocols used in SAN are:
- Fibre Channel – Fibre Channel is the most predominant SAN protocol. It provides high speed serial connections over fiber optic cables.
- iSCSI – iSCSI allows SAN over TCP/IP networks. This allows SAN to be built over existing Ethernet networks.
- FCoE (Fiber Channel over Ethernet) – FCoE allows Fibre Channel traffic to be encapsulated over Ethernet networks.
- InfiniBand – InfiniBand is a high-speed low-latency protocol that can be used for SAN.
Out of these protocols, Fibre Channel is the most commonly used protocol in enterprise SANs while iSCSI is more popular in SMB networks.
What are the different SAN topologies?
SAN topologies refer to the layout and interconnection of different SAN components. The main SAN topologies are:
- Fabric topology – All devices connect to a central fabric made up of SAN switches. This is the most commonly used topology.
- Direct attach topology – Servers connect directly to the shared storage without a switching fabric.
- Hub topology – Similar to fabric topology, but uses hubs instead of switches.
- Switched fabric topology – Uses multiple switches interconnected in a mesh or core-edge architecture.
- Director based topology – Uses intelligent director class switches for interconnecting large number of devices.
What are LUNs and how are they used in SAN?
LUN or Logical Unit Number is basically a logical representation of a physical storage device in a SAN. Some key points about LUNs:
- LUN masking is used to control which servers can see and access a given LUN.
- LUN mapping determines the relationship between a LUN and the physical storage it is mapped to.
- LUNs enable the physical storage to appear as locally attached logical drives to the servers.
- LUNs also add a layer of abstraction between servers and physical storage.
- LUNs can be thinly provisioned meaning physical storage is allocated only when data is actually written by servers.
By using LUNs, SAN administrators can efficiently manage storage allocation and isolation for multiple servers. LUN masking and mapping provides granular control and security.
What are device zones and how are they used in SAN?
Zoning allows logical segmentation of a SAN into smaller subsets called zones. The main purposes of zoning are:
- Segregate traffic and devices for security and isolation.
- Control visibility among devices.
- Allow different traffic types to use different fabrics, switches.
- Improve performance by partitioning complex environments.
Some ways zoning is implemented in SAN:
- Port zoning – Grouping devices based on switch ports.
- WWN zoning – Grouping based on World Wide Name identifiers.
- LUN masking zoning – Allowing access to only specified LUNs.
- IP zoning – Grouping based on IP addresses, used in iSCSI SAN.
Zoning hides devices from non-members to enhance security and prevent disruptions. It also reduces bandwidth contention on the network.
How does multi-pathing work in SAN?
Multi-pathing refers to ability to use multiple physical paths between a server and storage device for traffic distribution and redundancy. Following are some multi-pathing features in SAN:
- Path failover – Automatically switch to alternate path if one path fails.
- Load balancing – Distribute I/O across paths to improve performance.
- Redundancy – Provide high availability through redundant paths.
- Aggregated bandwidth – Combine bandwidth of paths for higher throughput.
Multi-pathing requires coordination between host OS multipathing drivers and firmware in SAN switches and storage arrays. Path management, monitoring and failover are handled transparently.
What is SAN virtualization?
SAN virtualization refers to abstraction and consolidation of physical SAN storage into logical storage pools. It provides following benefits:
- Pool physical storage from multiple devices into unified capacity.
- Apply features like thin provisioning, snapshots across diverse storage.
- Seamless data mobility between storage devices.
- Improve scalability through seamless storage expansion.
- Better utilization through thin provisioning and over allocation.
- Reduced downtime during storage maintenance.
SAN virtualization is implemented through intelligent virtualization software and appliances. It simplifies storage management in complex, large SAN environments.
What are the different ways to connect SAN and LAN?
SAN and LAN can be interconnected in following ways:
- Fibre Channel over IP (FCIP) – Encapsulates Fibre Channel traffic into TCP/IP packets.
- iSCSI – Runs SCSI block protocol over TCP/IP networks.
- Fibre Channel over Ethernet (FCoE) – Encapsulates Fibre Channel over Ethernet.
- NFS – Exports SAN storage over NFS to clients.
- Direct Fibre Channel Connection – Connects SAN switches directly to Ethernet switches.
Among these, iSCSI and FCoE allow organizations to converge SAN and LAN and use a single unified network. NFS exports file systems over LAN while block storage is accessed over SAN.
What are the different types of cables used in SAN?
Common cable types used in Storage Area Networks are:
- Copper Cables – Used for short distances up to 30 meters. 1 Gbps speed.
- Multi-mode Fiber Optic – Used for distances up to 2 kilometers. Speeds up to 10 Gbps.
- Single-mode Fiber Optic – Used for longer distances from 2 km to 10 km. Supports speeds higher than 10 Gbps.
- Coaxial Cables – Used for older 1Gbps Fibre Channel SANs. Up to 30 meter length.
Fiber optic cables are most commonly used since they support greater distances and higher speeds. Copper cables are cheaper but suitable only for short distances.
What are common SAN switching components?
SAN switches provide dedicated interconnection between servers and storage. Here are some common SAN switch components:
- Chassis – Houses switch electronics and connectivity slots.
- Power Supplies – Provide adequate power for switch operations.
- Fans – Provide forced-air cooling for switch components.
- Line Cards – Add network ports like 16Gb FC ports. Installed in switch slots.
- Switch Fabric Cards – Handle internal switch bandwidth and data transfer.
- Management Modules – Allow admin, monitoring and management of the SAN switch.
SAN switches also include software features like zoning, routing, virtualization etc. Advanced switches provide redundancy through components like dual power supplies, fabrics etc.
What are some common SAN disk array components?
Disk arrays provide consolidated block-level storage in a SAN environment. Some key components of a SAN disk array are:
- Disk drives – Hard disk drives that provide the actual storage capacity.
- RAID controllers – Implement RAID functionality across disk drives.
- Cache memory – Improves performance by caching frequently accessed data.
- Backplanes – Provide connectivity for disk drives to attach to controllers.
- Power supplies and cooling fans – Provide power and cooling to array components.
- Array controllers – Manage and control connectivity and functionality.
- Management interfaces – Allow monitoring, administration and configuration.
High-end SAN arrays provide additional components like advanced caching, redundant controllers, non-disruptive upgrades etc.
What are the essential factors to consider when designing a SAN?
Some key considerations when designing a SAN are:
- Required storage capacity and growth – Determine projected storage needs.
- Number of servers – Factor in all servers that will connect to SAN.
- Throughput and performance – Consider IOPS, bandwidth for each server’s workload.
- Availability and redundancy requirements – Determine RTO and RPO.
- Type of workloads – Transactional, sequential, VMs etc. impact design.
- Backup and disaster recovery needs – Replication, snapshots etc. add design factors.
- Data security – Encryption, zoning, LUN masking security considerations.
- Management overhead – Ease of management requirements affect choices.
Final design depends on balancing and meeting all infrastructure, performance, availability and management requirements.
What are the benefits of using HP SAN solutions?
Some key benefits of HP’s SAN storage portfolio include:
- Broad product portfolio – Extensive range from entry-level to enterprise SAN solutions.
- Data services – Advanced data management features like snapshots, remote replication etc.
- Management – Centralized management console HP OneView for automation and orchestration.
- Reliability – Enterprise class availability, redundancy and resilience.
- Scaling – Modular scalability to grow capacity and performance on-demand.
- Flash optimization – Integrated flash for intelligent data tiering and caching.
- Networking – Integrated Fibre Channel and Ethernet networking capabilities.
- Support services – Robust 24×7 support services and documentation.
HP SAN solutions like 3PAR, MSA, StoreVirtual etc. enable simplified management, scalability and high availability for critical applications.
What are the different HP SAN product lines?
Some of HP’s major SAN product lines include:
- HP 3PAR StoreServ – Enterprise SAN storage arrays for Tier-1 workloads.
- HP MSA Storage – Cost-optimized SAN arrays for SMBs.
- HP StoreVirtual – Software defined storage on standard hardware.
- HP StoreOnce – Backup and recovery focused disk arrays.
- HP StoreFabric – Fibre Channel, iSCSI and Ethernet SAN networking.
- HP StoreEasy NAS – File-based network attached storage systems.
These product lines cater to the diverse storage needs of enterprise data centers to small businesses. The solutions are backed by HP’s service and support expertise.
Conclusion
SAN is a dedicated high-speed network that allows servers to access consolidated block-level storage systems. By providing centralized storage pools, SAN enables organizations to efficiently manage large data growth, support business applications, enhance utilization and availability of critical data. Leading enterprise vendors like HP offer feature-rich SAN products and solutions suitable for organizations of all sizes. When designed and implemented appropriately, Storage Area Networks enable businesses to align storage infrastructure capabilities with enterprise goals.
