NetApp module number three! I have to admit I wasn’t a total fan of this module, don’t get me wrong I love learning new things. However, the person talking in this module was a few times inaudible to me, as well as having to correct himself a lot and speaking in one tone. I find that incredibly difficult to follow, plus this subject isn’t the most exciting :-D, anyway let’s begin 🙂
NAS and SAN
Heading back into some of the things talked about in the Storage Fundamentals module, but expanding on them a bit more.
Data Storage and Data Networking
- Storage: Storing and protecting data for as long as you need it – data over time
- Information repository
- RAID, JBOD
- Networking: Transporting data from one location to another quickly and reliable – data over distance
- Information movement
- Hubs, switches
Direct Attached Storage/DAS
Hello, DAS our old friend :-). Simpliest type of storage outside the system it is used. Simple, self contained system where the application, file system and storage are connected directly to each other. Two methods were developed to provide additional storage and data access across mutiple users, workstations, they are; Network Attached storage/NAS and Storage Area Networks/SAN.
Network Attached Storage/NAS
In NAS the device is attached directly to the network, will appear as another system. A system where files are stored, because it’s on the network other machines are able to access it, a single NAS device could provide data to a variety of network application machines.
Storage Area Network/SAN
In a SAN system storage appears to the network as another hard drive that is shared among various systems.
NAS versus SAN
- File system and storage in one device which is then connected to the network
- Easier to network
- Simplier to manage
- Storage appears to other computers as a file server
- Storage is on its own network for tranporting files.
- Work of transporting files is moved off the LAN and on to the dedicated fabric of the SAN.
- Storage appears as a disk drive that can be mounted on computers that use it.
Both NAS and SAN have their own strengths.
NAS: Connections, Attachments and Access
Client computers are connected via LAN. The NAS system is attached to the LAN network both the filer and the storage systems contained within the NAS system.
- Data treated as files/file access
- Files managed within the NAS system
- Management simplified
SAN: Connections, Attachments and Access
Client computers are connected via LAN. A SAN network is attached to the LAN network. The SAN network is a network of hardware that is dedicated to their data storage. Usually SAN systems are more flexible and handle disaster recovery better than NAS systems but can usually be more difficult to set up.
- Broken up into blocks and stored as data blocks/Block access
- Files managed outside the SAN system
- Configuration flexible
- Performance high
SAN Connections: iSCSI, SAS and FC
Which stands for “Internet small computer system interface”, IP based standard that is the primary alternative to FC (fibre channel). Uses standard cables and switches and can send signals longer distances. Supports all ethernet interfaces. It has high speeds and is the less expensive choice. However, it has low dependability.
Which stands for “Serial attached SCSI”, uses aerial cables and carries SCSI packets. It is created with serial cables rather than ethernet cables. Data cables cannot be longer than 8M and the hard ware limits the number of connections that can be provided. Is inexpensive and more reliable than iSCSI.
Which stands for “Fibre channel”, protocol designed to allow the SAN environment to signal information. Can use either optic cabling, fibre optics or copper wiring. FC is very reliable and scalable. Enables you to add storage without destructing operations. Is very flexible.
FC: Topologies and Zoning
- FC-P2P (point to point): Is the simpliest topology. Host server is connected directly to the storage appliance. However, it’s very limited.
- FC-AL (arbitrated loop): All devices are within a loop which can cause problems because if there is a failure of any one device it can cause a break in the loop. Allows more connections than FC-P2P.
- FC-SW (switched fabric): All devices including the host and storage systems are interconnected through fibre channel switches, these switches maintain the state of the fabric providing optimized interconnections and security.
Zoning: A group of fibre channel ports that can communicate with each other only if their in their zone or zones.
- Hard zoning: zone members are defined by a fibre channel switch and its ports. Offers improved security and can be easier to manage.
- Soft zoning: A cable can be moved from one port to another without reconfiguring the zone. Offers excellent flexibility and scalability.
Does any one of my classmates understand this part of the module? The topologies and zoning, I’m having a hard time wrapping my head around. It always catches me by surprise how indepth you can go with a single aspect of networking and a lot of the time I lose myself in it and get confused!
File and Block Storage, High Availability and High Performance Computing
File Storage versus Block Storage
- Block Storage
- Uses configurable length or block size
- Set standard chucks of data
- Better flexiblity and high performance
- Administrators can choose the configuration that best suits their needs
- More complicated
- File Storage
- Much simplier for the end user and the system
- Less flexible
- Sacrifices performance to achieve simplicity
- Data organised as files
A nice comparison they used in the module to compare the two, was the difference between manual driving (block storage) and automatic driving (file storage). Thought I would mention it because anyone struggling with understanding file and block storage would make some sort of sense of it from that excellent comparison :-).
Although this module was definitely not my favourite one, it was still a helpful and informative module. It is also helpful writing these summarised blogs, helps me go through the information of the module and understand it fully. Four modules left to go :-), Cloud fundamentals next :-).