Failover at multiple level in storage networks

Storage networks can be broadly classified into 3 levels and the fail over or Redundancy feature is very important aspect of IT storage business and it is implemented in every interconnecting components in the networks.
Host or Server(s) Level
Network Level
Storage sub-system(s) Level

Fail-Over:
If the data passage path of any of the component in the storage networks fails, the auto-mechanism that provides an alternate path instantly to avoid the data loss is called fail-over.
Example: If a component such as a RAID controller module or a cable fails, or an error occurs on the data path to the preferred RAID controller module, virtual disk ownership is moved to the alternate non preferred RAID controller module for processing. This failure or error is called failover.

Host or Server Level:
Hosts or servers are associated with few interconnect peripherals such as Host Bus Adapter [HBA], Ethernet adapters et al. some common fail-over feature implementations that you see is at the HBA device in the form of Fail-over driver such as MPP or MPIO [Multi Path driver].
Another stage of fail-over implementation could be to the entire host or server in the form of Clustering, Microsoft Clustering or Linux or Solaris or Unix clustering.

Network Level:
At Switches or Routers, we can provide fail-over by connecting one port or path of the servers & storage sub-systems to one switch port & another port or path connected through another switch port. thus we need at the least two switches to handle the Preferred path & Alternative path of data passage.
usually such setups are know as High Availability Fail-over setup.

Sub-system Level:
Within the SAN storage sub-systems, there are multiple components such as RAID Processors or controllers, Hard disks, Drive trays, power supplies et al.
At Hard disk level , RAID & Hot sparing is used in co-operation with RAID processors as fail-over.
At Drive tray or Enclosure level, there will be dual Service Modules that act as fail-over.
At the RAID Processor or Controller level, there will be Dual RAID processors or Controllers that provide fail-over mechanism.

Fail-over is very vast concept and there are plenty of ways to implement it at different components of the storage networks. for more information you can always buzz me on Email.

IBM Storage Products

NOTE: IBM has comprehensive range of storage hardware & software products such as servers, SAN, NAS, Switch, Tape libraries, switches & SAN arrays, NAS devices etc. so here am listing only few storage specific products.

IBM Disk storage subsystems
Enterprise systems - DS6000 and DS8000 family
DS6000 series
DS8000 series
DCS9550

Mid-range systems - DS4000 family
DS5000
DS4800
DS4700 Express
DS4200

Entry level systems - DS3000 family
DS3200
DS3300
DS3400

Enterprise SAN directors [High end switches]
For highest availability and scalability enterprise solutions.
IBM System Storage SAN768B
IBM TotalStorage SAN256B
IBM TotalStorage SAN140M
IBM TotalStorage SAN256M

Mid-range SAN switches
For scalable, affordable SMB and enterprise solutions.
IBM System Storage SAN80B-4
IBM System Storage SAN64B-2
IBM System Storage SAN40B-4
IBM System Storage SAN32B-3

Entry SAN switches
For simple, affordable small and medium business (SMB) solutions.
IBM System Storage SAN24B-4 Express
IBM TotalStorage SAN16B-2

IBM Express Model SAN switches
For affordable, simple-to-use small and medium business (SMB) solutions.
IBM System Storage SAN24B-4
IBM TotalStorage SAN16B-2

Tivoli Storage Manager
Manage risk through complete storage management with enhanced performance and access for Sequential Disk. Manage complexity with encryption key management. used by more than 21,000 customers.

OEM Storage Management softwares
Basically OEM storage product software marketed with IBM logo.

IBM TotalStorage Productivity Center
Identify, evaluate, control and predict the growth of data through its lifecycle to meet storage service levels.

IBM System Storage Virtualization
Designed to help simplify storage infrastructure, optimize storage utilization, and enable business to adapt quickly and dynamically to variable environments

HP Storage Products

NOTE: HP has comprehensive range of stroage hardware & software products such as servers, SAN, NAS, Switch & HBA software, HBA's, switches & SAN arrays, NAS devices etc. so here am listing only few storage specific products.

Disk Storage Systems [SAN]

XP Disk Array - High Level
[HP StorageWorks XP24000 Disk Array, XP20000 Disk Array, XP12000 Disk Array, XP10000 Disk Array]
• Bulletproof storage for 24x7 business continuity demands
• Massive consolidation for greater efficiency
• Virtualization platform for internal and external data

EVA Disk Arrays - Mid-level
[HP StorageWorks Enterprise Virtual Array 8100, EVA6100, EVA4400, EVA4100 & EVA Software]
• Powerfully simple enterprise class storage
• Affordable and virtualized storage with a low entry price and low total cost of ownership
• Reliable and available

MSA Disk Arrays - Entry level
[HP StorageWorks Modular Smart Array 2000sas, MSA2000fc, MSA2000i & Storage Resource Management Software (SRM)]
• Flexibility to start small and migrate drives & enclosures into larger configurations
• Increase server capacity
• Modular design enables expansion

NAS Systems
[HP All-in-One AiO1200r SATA, AiO1200r SAS, AiO600, AiO400t, AiO400r,AiOSB600c]
• Unbelievably simple: No storage expertise required
• Uniquely affordable: A complete storage solution
• Unquestioningly reliable: Integrated data protection and HP reliability

Scalable NAS

• Scalable, Available Enterprise NAS
• Windows and Linux File Serving
• Oracle over NFS, Microsoft SQL Server Consolidation

Switches
B-series [Fabric switches, Blade switches, Director switches]
• B-series switches and directors are used by small departments and global organizations to access and share data in a consolidated, manageable, and a scalable manner.
C-Series [Fabric switches, Blade switches, Director switches]
• C-series family of multilayer directors and fabric switches is a comprehensive line of SAN switches that provides an effective way to access, manage, and protect growing information resources.
• C-series switches are basically CISCO switches marketed by HP.

HP Storage Software

• Storage Resource Management Software (SRM)

• HP StorageWorks EVA Device Management Software
• HP StorageWorks EVA Replication Software

• HP StorageWorks XP Replication Software
• HP StorageWorks XP Device Management Software

• HP Storage Data Protection and Recovery Software
• HP StorageWorks Storage Replication Software
• NAS Device Management Software
• B-series Switch Device Management Software
• C-series Switch Device Management Software

Fabric-side or Switch-side Implimentation in SAN

For More info & your Feedback, contact Email ID: storagetrendz@gmail.com.

FC SAN:
* FC Switch or Fabric in SAN architecture consists of Ports (GBIC or SFP in it), FC protocol stack, Fabric Operating system & Fabric Controller units.
* The Fabric provides basic functionality of connecting multiple Hosts & Storage Sub systems together and manages the communication between them. using Fabric switch topology, about 16 million devices can be connected together in SAN Network.
* Each port on the Swicth is having Unique Address called as World Wide Node Name (WWWN) & World Wide Port Name (WWPN).
* In addition, Fabric provides advanced functionalities as given below,
1. Multi casting & Broad casting services.
2. Name Server Database services.
3. Login Services.
4. Register state Change Notification [RCN] Services.
* Fabric Zoning is the important feature provided by FC switches, By appropriately creating zones and assigning devices [HOST + storage LUNs], an administrator can create a network in which individual hosts cannot access storage devices that are controlled by another host in the FC network.

iSCSI SAN:
* iSCSI Switch or Ethernet Swicth in SAN architecture consists of Ports (ethernet ports), TCP/IP & iSCSI protocol stack, switch software & Controller units.
* The ethernet iSCSi swith provides basic functionality of connecting multiple Hosts & Storage Sub systems together and manages the communication between them.
* Each port on the Swicth is having Unique Address called as World Wide Unique Identifier (WWUI) & there are three different address format, iqn (iscsi Qualifier Name format by CiSCO), eui (Extended Unique Identifier by IEEE), naa (Network Address Authority by T11 organization).
* In addition, Fabric provides advanced functionalities as given below,
1. Uni-Casting, Multi-casting & Any-casting services.
2. Routing Database services.
3. Login Services.
* VLAN Configuration which is similar to Fabric Zoning in FC SAN.

Note:
* More info. on FC Fabric, Zoning & iSCSI Networking will be published in upcoming Posts.